"Great Scott!" was the spontaneous exclamation of both the newcomers. "Where did it come from?"
"You tell," replied Billie. "Lucia says it was not here an hour ago. Neither has any one been in the room so far as she knows."
"Has she been here all the time?" asked Adrian.
"No, she was with Josie in her room for a time; but the door into the patio was locked."
"Some one might have come in through the window."
"A fat chance, isn't there!" laughed Billie, pointing to the only window in the room which was protected with long and heavy iron bars, set so closely together that a child would have had trouble in squeezing through—much less a man.
"Does look a little difficult," replied Adrian.
"Worse than difficult. Impossible," was Donald's comment.
"Did you hear any noise?" asked Billie of Lucia.
"None whatever."
"And you have never seen the box before?"
Lucia wrinkled her brows and thought deeply.
"Do you know," she finally said, "I have a sort of a dim recollection that, away back in my childhood somewhere, I have seen it or one just like it."
"Away back in your childhood," laughed Donald, "couldn't have been so very far, Señorita."
Lucia made a little grimace.
"I'm nearly seventeen," she said.
"Botheration!" said Billie. "We are not here to discuss ages, but to find out how this box came here. I have no doubt that Lucia has seen many similar boxes in her time."
"Well," asked Donald, somewhat nettled, "what do you propose to do?"
"In the first place, I want to search the house."
"That's a good idea," declared Adrian. "DonnaLucia, will you lead the way?"
"Certainly. Right this way; but don't go into father's room. I know there is no one in there. One of the servants has been with him every minute of the time."
Headed by Lucia, the boys explored the house from top to bottom, but not a sign of any one could they find. So far as they could determine, the box must have come in of its own self.
"I'll tell you one thing we can and must do," said Billie, after they had returned to the library. "We must keep a watch in this room to-night. Whoever put the box here may return."
"Right!" from Don. "You do have occasional lucid intervals, Billie."
Billie grinned, but made no reply.
"I think we may all stay here for a few hours," suggested Lucia. "Father is so much better that I think we may have a little music. I will play some accompaniments on the guitar and Josie can sing."
"That will seem a good deal like being back in the States," declared Adrian. "With the Stars and Stripes flying over my head, a brigade of American troops on guard and an American girl singing, I can almost forget I am on Mexican soil."
"How about the accompanist?" queried Billie.
"Oh!" laughed Adrian, "we're quite willing to adopt her. Hey, Donald?"
"Don't ask me, Ad. Ask Billie."
"I am sure we could do no better," was Billie's gallant reply.
Lucia's suggestion was carried out and for a couple of hours there was a merry little party under Santiago's hospitable roof. Even the mysterious box was forgotten and the young people were giving themselves up to a jolly good time, when suddenly there came a scream which caused every one to turn their eyes toward the room in which the sick man was supposed to be lying.
But there in the doorway he stood, his long night robe reaching nearly to the floor and his thin black hair standing almost on end.
"Father!" cried Lucia, rushing toward him "What is it?"
He waved her off, but made no reply, while with his long bony finger he pointed at the brass-bound box.
"Where did it come from?" he asked in a shrill, querulous tone. "Who brought back my secret casket?"
"Yours?" came from every one in the room.
"Yes! Mine! Mine!!" he almost screamed.
"He's raving!" cried Josie. "Can't some one do something for him?"
"No," he replied, and his voice became more calm, "I am not raving. I know whereof I speak. Quick! Let me look within it to see that all is safe."
"It is locked, Father," said Lucia, coming to hisside, "and we have no key."
"I can unlock it," he cried. "I can unlock it. Give it to me. Give it to me."
He staggered forward and seized the box in his hands. For several seconds he fumbled with it, turning it first upon one side and then upon another, and at last raised the lid. He thrust in his hand and then stopped as one stupefied.
"Empty! Empty!" he gasped in an almost audible whisper. "The plan of Montezuma's mine is gone! Gone!!"
A moment he stood and gazed around upon the faces of those in the room and then collapsed upon the floor.
Quickly the boys picked him up and carried him to his bed and the attending physician was summoned.
Billie picked up the box and examined it curiously.
"I wonder how he opened it?" he mused. "There must be some sort of a spring somewhere."
He felt the box all over, but could find nothing. Then he closed it and set it upon the table. A moment later Donald picked it up and tried to open it, but it was locked fast.
"Nothing but mysteries," he said. "I'm getting tired of them. But before anything else happens, I'm going around and notify Don Esteban that the box is here."
"I'll go with you," said Adrian.
"No, you'd better stay here. I'll take a mozo with me."
He ran hastily down the stairs and a minute later the boys heard the gate close behind him.
"I guess this is the quickest way," thought Donald as he gained the sidewalk. "I'll not bother with a mozo. With American soldiers on guard and my automatic in my pocket, I have nothing to fear."
A couple of minutes later he was ringing the bell at Don Esteban's house. He was hastily admitted and at once conducted to that gentleman's presence, where he narrated hastily what had occurred at the other house.
"Who is this old man?" Don Esteban asked of Donald.
Donald explained as best he could.
"Which is mighty little," he declared when he had finished. "He is the greatest mystery we have ever encountered. There is no doubt that he is an Indian, but he speaks English like an Englishman."
"I must go and see him at once," declared Don Esteban, rising.
"I don't think you can, sir, to-night. I don't think the physician would permit it."
"Well, then, the first thing in the morning. I thank you, young sir. Won't you have a glass of wine before you go?"
"No, I think not," replied Donald. "I've neveracquired that Mexican habit yet. Good night, sir."
He left the house feeling greatly relieved that he had reported the finding of the box and walked slowly along whistling merrily. As he turned off the street upon which Don Esteban lived he heard soft footsteps behind him and turned hastily.
But he was too late.
Before he could see who it was, or ere he could cry out, a cloak was thrown over his head and he was picked up and carried away bodily.
Donald was not the boy to give in without a struggle, but kick and squirm as he might, he could not free himself. Presently those who were carrying him stopped and laid him on the sidewalk. Then he heard a knock and a gate opened. Then he was lifted up again and, almost before he knew it, he was thrust into a little room—a closet it seemed—and the door closed upon him.
It was a hot night and the little place was stifling.
"I'll smother if I don't get out of this," he muttered.
Slowly he unwrapped the cloak from about his head and at last freed himself completely from its folds; but he secured little relief from the heat.
The room could not have been more than six feet square and it did not take Donald long to run his hand clear around the wall.
There was only one door, that through which he had been thrust, and it was locked. He poundedupon it, but to no avail. Then he sat down to think.
"There is certainly no use to sweat myself to death," he told himself. "I'd better be as quiet as I can. There is air enough coming under the door so I won't suffocate, so I might just as well wait and see what will turn up."
He ran his hand all over his automatic and found it in good shape. Then he leaned back against the wall opposite the door and waited. Ten minutes later the door was suddenly yanked open, another figure was bundled into the closet and the door slammed shut, almost before Donald could think.
A muttered imprecation was the only intimation that the figure which had been so unceremoniously bundled into the closet was alive.
"Who are you?" asked Donald in Spanish.
"Let me out of this," was the unsatisfactory response in English.
"Oh!" from Donald. "You are an American. Well, keep still and I'll help you to get rid of the blanket."
He grabbed hold of the covering and the newcomer was soon uncovered.
"Now, then, who are you?" asked Donald again.
"I'll show you who I am if I get hold of you," was the uncivil answer, and an arm shot out.
"Now look here," said Donald, "if you don't stop that I'll let daylight through you. We are in a bad box and the only thing to do is to make the best of it."
"We?" exclaimed the newcomer. "Why do you say we?"
"Because I am a prisoner the same as you are. Now, who are you?"
"I'm Lieutenant Grimes of the general's staff. Who are you?"
"I am Donald Mackay, on a special mission for Gen. Funston."
"How did they get you?"
"Kidnaped me on the street. How did they get you?"
"Same way. I had just left the general's quarters."
"I can see that some one might want to capture you, lieutenant, but I cannot see what they want of me."
"How long have you been here?" asked the lieutenant.
"About half an hour. By the way, are you armed?"
"No; they took away my weapons. How about you?"
"I have my automatic. I'd have used it whenyou came in, only you were dumped in so suddenly."
"What do you suppose the game is?"
"I don't know; but we'll find out. I've been in tighter places than this—but no hotter," after a pause.
"Have you tried to get out?"
"Yes; but it was too hot work. The door seemed pretty strong."
"Perhaps the two of us might force it," suggested Grimes. "I'm a pretty husky chap."
"We might try," replied Donald. "The place is so narrow we can get a good brace."
They put their feet against the opposite wall and pushed against the door.
"We'll never make it that way," said the lieutenant. "We'll have to throw ourselves at it."
"Not much room for that, Lieutenant, but you give the word and we'll have a try."
Getting their bearings as well as they could in the dark, they drew themselves back and then literally threw themselves at the door. It gave way with a snap and both fell to their feet on the outside.
Quick as a flash they were on their feet, Donald with his weapon ready for instant action.
But there was no one in sight.
"That's mighty funny!" exclaimed the lieutenant. "Lock two strong men up in a place like that and not guard it."
"It's a mighty good thing for us they didn't,"laughed Donald. "I wonder where we are?"
He glanced about the room which was dimly lighted by a couple of lamps, fastened to the wall by brackets. It was well—yes, elegantly furnished. At one side of the room was the closet out of which they had just emerged, while at the opposite side were three doors. On a third side were two windows and the fourth side was a plain wall.
"Not a bad-looking place," observed the lieutenant.
"Not at all," echoed Donald, "and there seem plenty of means of exit."
"Sure, my boy; and if it's all the same to you, we'll go. The sooner I get back the quicker I'll be able to start something in this direction. Come on!"
They crossed over to the doors and tried the first one. It was locked. They tried the second and it opened into another closet.
"Three times and out," laughed Donald as he took hold of the knob of the last door.
It yielded to his touch and he opened it gently. Then he quickly and quietly closed it.
"What's up?" asked the lieutenant.
Donald put his fingers to his lips.
"How many?" queried Lieut. Grimes.
"Three," was the whispered response. "Let's hear what they have to say."
He opened the door a crack, through which theycould see three men seated at a table. One wore the uniform of a Mexican officer, the other was dressed in Mexican costume, while the third was unquestionably an American, although they could only see his back.
"I have carried out my part of the agreement," the American was saying, "and now I want my money."
"How do we know you have?" asked the officer.
"Haven't I put Gen. Funston into your hands?"
"We are not sure it is Funston," said the other.
"Then bring him out and look at him. You know the general when you see him, don't you?"
"I think so, although I've never seen him but once."
"Well, that is he, all right," declared the American.
Donald turned and looked at his companion. Then he chuckled.
The lieutenant said nothing, but stroked his whiskers which he wore in exact imitation of his chief.
"Lucky for the general," he whispered, and Donald nodded his head that he understood.
The two Mexicans exchanged a few words under their breath which Donald could not hear and then the officer took from his breast pocket a large wallet, from which he counted out ten bank notes. They were yellow backs and Donald was not at all surprised when the officer said:
"Here are ten one-thousand-dollar bills in Americanmoney. We believe you are telling us the truth, as your words are corroborated by the men who brought him here. But if you are playing us false, we shall know how to reach you."
The American shrugged his shoulders as he took the bills, rolled them up nonchalantly and placed them in his trousers pocket.
"You can find me at the Hidalgo Hotel whenever you want me," he said, "and now I must be going."
He arose from his seat, and as he did so, Donald caught sight of his face. It was the mountebank, Strong, but in his stylish clothing Don had failed to recognize him.
"Great Scott!" he muttered to himself, "the plot thickens!"
"What's that?" queried the lieutenant, who caught the muttered exclamation.
"Nothing much," replied Donald as the three men walked toward a door in the farther end of the room and he was enabled to speak without being heard, "only that is the man I'm looking for. Let's get out of the window and see if we can't head him off."
He closed the door and turned the key which he had quietly taken from the other side.
The windows were open and they looked out. They were on the side of the house overlooking a good-sized lawn.
"That's the reason they are not barred," explainedDonald. "Had they been front windows, we might as well have been in jail. You go first and I'll cover the retreat."
Lieut. Grimes sprang into the window and lowered himself to the ground, just as a hand turned the knob.
"Good-bye!" muttered Donald. "Sorry I can't wait to receive you," and he followed the lieutenant.
On the ground they could hear the men trying to open the door and as they sped across the lawn toward a high brick wall, the door gave way with a crash and they could hear surprised voices.
"They have discovered our wreckage!" cried Donald. "Over the wall you go!"
"You first this time," said the lieutenant.
"No, you first. I can boost you up, but I couldn't pull you. You can pull me."
The argument was good and the lieutenant acted upon it.
A minute later he was on top of the wall.
"Great Cæsar!" he exclaimed. "There's nothing under me but water."
"Never mind that," was the response. "Haul me up."
The lieutenant leaned down and gave the lad a hand.
"Here we are," he said a minute later. "We can't jump in, for there is no knowing where we are."
"Sure," from Donald. "Let's run along thewall."
This they did for about a hundred yards and then the wall ended abruptly against what appeared to be an abutment.
"We must act quickly," declared Donald. "They think you are Funston and won't hurt you. Keep up the deception. I'm going to swim for it. I'll have help here just as quick as I can. So long," and, throwing off his coat, he jumped into the water some twenty feet below.
When Donald struck the water he allowed himself to go clear to the bottom, as he wanted to find out just about how deep it was.
It was, as he had expected, about the depth of the water in the harbor and he made up his mind that he could not be far from some of the wharves that constitute the water front.
When he came to the surface, he struck out away from the wall, and by the light of the moon was soon able to see the vessels in the offing. He could also see that he was well north of the principal docks.
"I guess I'll land at the first place that offers,"he thought, "and find my way to headquarters from there."
He struck out lustily, but had not been swimming more than a couple of minutes, when he heard the sharp exhaust of a gasoline launch.
Realizing that it must be an American craft, he shouted at the top of his voice.
At first there was no response, but as the boat came nearer and he shouted even more loudly, a friendly hail came over the waters.
"Where are you?" came the voice as the boat came to a stop.
"Here, to your port side," he replied.
The launch was started again slowly and Donald was soon able to make himself visible.
"Who are you?" was the first question pumped at him by the officer in command.
"Special messenger for Gen. Funston," was the response.
"Where is your uniform?"
"I'm not a soldier. I am a civilian."
"A likely story," snapped the officer, who chanced to be an ensign.
"I can't help how likely it is," snapped Donald in return. "It's true, and I want to be put ashore as quickly as possible. I have an important message and the safety of one of his staff is involved. There is also a plot on foot to capture the general himself."
"Nonsense! And besides, I can't put you ashore.I am carrying a message to Admiral Fletcher."
"But my business is important," insisted Donald.
"So is mine," declared the ensign.
He ordered his launch full speed ahead in the direction of the flagship.
"It's pretty tough," commented Donald, "but I'll prove I am right when I get to the ship."
"I hope so," was the reply. "I haven't anything against you and you may be telling the truth, but I can't take any chances."
Fifteen minutes later they drew up beside the flagship.
"Up you go," said the ensign, motioning Donald up the ladder. "I'll present you to the officer of the deck," which he quickly did.
"Here's a man I picked up in the water, sir, who says he has a message for Gen. Funston, but I had no time to put him ashore."
"Looks more like a boy than a man," replied the officer. Then to Donald: "What's this about you having a message for Gen. Funston?"
Donald repeated what he had told the ensign.
"What's that?" asked another officer, coming forward out of the shadow of the after turret.
The first officer saluted.
"Tell the Admiral your story, my lad," he said.
Again Donald repeated his story, this time going more into detail.
"Come with me," ordered the Admiral, and heled the way to the wireless operator.
"Get into communication with Gen. Funston at once," was the admiral's order.
"Here he is, sir," was the report a couple of minutes later.
"Ask him if he has three American boys on a special mission."
The answer came back promptly that he had.
"Ask him if Lieut. Grimes is missing."
Again came back the answer that he was.
"Tell the general that we have one of the lads on theArkansas, and that he has had a strange adventure. Tell him I will send the lad ashore immediately."
"Thank you, sir," said Donald. "I knew some one would know what to do."
"You're a brave lad," was the Admiral's comment, "and I shall be glad to hear the end of the adventure. You and your companions must come out and dine with us as soon as your mission is ended."
Donald thanked him for his kindness and hastened to the launch which was to take him back.
Twenty minutes later he stood before Gen. Funston.
"You seem to have been in the water," was the general's first words.
"Yes, sir," laughed Donald. "I jumped from awall north of town, leaving Lieut. Grimes on top of it."
"What! Lieut. Grimes on top of a wall? How did he get there?"
"He was kidnapped, sir! It was a case of mistaken identity!"
"Mistaken identity! I don't understand!"
"They took him for you, sir, because his beard is trimmed like yours."
The general smiled grimly.
"Think I shall have all my staff officers do the same," he commented. Then more seriously: "Can you lead us to the house?"
"I'm not sure about the house; but I can take you to the stone wall from which I jumped. That ought to guide us to the house."
"Right," said the general.
He called another member of his staff and gave a few brief orders.
In another ten minutes two launches loaded with regulars and armed with a rapid-fire gun in each, steamed swiftly up the harbor.
"There's the wall!" exclaimed Donald a few minutes later, "and there's where I jumped," pointing to a spot near the abutment.
The officer in command headed the boats for the shore.
"It is not only a question of freeing Lieut. Grimes," said the officer, "but we also want to capturethe conspirators. This is a much more serious matter than Gen. Funston is willing to admit."
"Then if you will take my suggestion, sir," said Donald modestly, "I would let a few soldiers go over the wall as well as entering the front of the house."
The officer looked up twenty feet. The wall was absolutely perpendicular and as smooth as the side of a house.
"I'm afraid none of my men can scale it," he said.
"Can't we throw a grapnel over it, sir?"
"We might; but it would be a very slight hold."
"If you can make it hold at all," laughed Donald, "I'm willing to make the effort. At best I can only fall back into the water."
"True," declared the officer. "We'll try it."
A grapnel was tied to a long line, such as is used in tying the launch to the shore, and after several vain attempts the grapnel caught in the top of the wall.
Donald sprang forward and tested it with his weight and it held. Then, without another word, he braced his feet against the wall and in almost less time than it takes to write it, he was at the top.
"Do you see any one?" asked the officer from below.
"No, sir; but there is the sound of pacing footstepson the walk that runs along the side of the house."
"Good! Now make fast the grapnel and we will see if there are a dozen men here who can climb to the top."
The dozen were quickly found and they were soon at the top of the wall. The officer finally decided to add to their armament one of the rapid-firers.
"If there is any resistance," he said, "we'll knock the side of the house in."
"What shall I do?" asked Donald.
"You'd better come back into the boat. You can help us to enter the house in front."
Donald slid down the rope and the expedition quickly made a landing. Silently, so as not to alarm those within the house, the men took their way to the front of the mansion, which was at once recognized as one of the finest in Vera Cruz.
"Do you know who lives here?" asked the officer.
"No, sir," replied Donald.
"I was told it was the residence of one of Huerta's generals," said a soldier. "It was pointed out to me the first day we landed."
"Good!" from the officer. "I shall now have no compunction about entering the place."
With Donald and a couple of soldiers, the officer approached the door and gave a vigorous knock.
There was no response and he knocked again.
"Who is there?" finally came a voice, evidently a mozo.
"An American officer. Open the door in thename of the law."
There was a still further delay and then another voice asked: "How do we know it is an officer?"
"Open and find out, before I force the door."
There was a still further delay.
"It's a good thing we guarded the rear," said Donald. "They are evidently trying to gain time to spirit Lieut. Grimes away, thinking it is Gen. Funston."
"True," said the officer. "We'll wait no longer. Corporal, force the door!"
The corporal placed a small stick of dynamite under the door and fixed a fuse.
"Step back a little," he said.
All obeyed, when at the instant the door was thrown open and a hand, in which was an automatic revolver, was thrust out, directly in the face of the officer.
But quick as was the action, Donald was not taken off his guard.
With a single swift blow he struck the weapon into the air.
At the same instant a fusillade from the rear of the house gave evidence that the men stationed upon the wall had done their work.
Having released Lieut. Grimes and taken the plotters into custody, the next task was to locate Strong, the mountebank, and to solve the mystery of the box.
Outside the one exclamation which Donald had uttered when he recognized Strong as the third of the plotters, he had not betrayed his secret to any one, and when Lieut. Grimes told his story to Gen. Funston and described the American, Donald vouchsafed no information which might help to apprehend him.
"The plotter told the Mexicans that he could be found at the Hidalgo Hotel whenever he was wanted," explained Lieut. Grimes. "While he may have lied about it, I think we should send a force and try to locate him."
The advice was acted upon and a corporal and four soldiers sent to the hotel, but to no purpose. No such man was known there.
"What was the use of my saying anything about it?" asked Donald of the other two boys when he returned to Santiago's house and narrated to them the story of his evening's adventure. "I was sure he was not there and I have no idea where heis; but we'll find him and the ten thousand dollars given him by the Mexicans for his treachery."
"That's right, Don," was Billie's comment. "If you can get that money and I can get my ten thousand pounds, this trip won't be so bad."
"In the meantime," said Adrian, "I propose that some of us go to bed. It's nearly two o'clock and there is mighty little chance that any one will try to steal the box again."
"I think you are right," said Billie. "We might as well all go. The doctor is still with Santiago and will stay until he is better. It isn't at all likely that any one will try to come into this room while he is here."
Billie voiced the unanimous opinion, and a few minutes later the young people had all sought their beds, leaving instructions with the physician and the servants that they were to be called if any change for the worse occurred in Santiago's condition.
It was probably two hours later, just about daylight, that the entire household was awakened by a terrible shriek and one of the maids rushed out into the patio.
The boys came to their feet with a bound and hurried from their room on the ground floor, while the others appeared at the head of the stairs.
"What is it?" asked Donald as soon as he could quiet the shrieking maid. "What are you yelling about?"
"Oh, señor!" she cried. "I have seen the devil."
"Nonsense," laughed the boy. "You had a nightmare."
"No, señor. It was the devil. He had horns and a tail and he had the little box under his arm. I saw him!"
"The box!" cried Billie. "Quick, Lucia, look and see if the box is gone!"
The girl rushed back into the library and she, too, gave a shriek.
"It's gone!" she cried. "It's gone!"
The boys sprang up the stairs three at a time and into the library. Lucia was right. The box was gone.
"It must be the old boy, sure enough," said Billie, "or at least one of his imps." Then to the maid: "How did he get in?"
"I don't know, señor. I only saw him go out. He went right through the door without opening it."
"Nonsense!" from Donald. "His Satanic majesty might go through a solid door, but the box wouldn't. There is some other explanation."
"But who could it be?" queried Lucia in great fear.
"Some one who knows the house," declared Adrian emphatically. "He may have put on some masquerade costume just to frighten these superstitious servants in case he was discovered."
"I believe Ad is right," agreed Donald. "What do you think, Billie?"
"Maybe, Don; but I have a theory of my own.If I am right, I can work it better if I tell no one."
At this moment the physician entered the room.
"How is Santiago?" asked Donald.
"Better! He has gone to sleep, and if he is not disturbed, I expect him to be greatly improved when he awakens. I should not be surprised if this were the turning point in his illness."
"Then we had all better go down on to the first floor and leave him alone with his nurses."
"I'd give a good deal to know where Strong is," remarked Donald as they were drinking their coffee an hour later.
"So would I," declared Billie. "I believe, if we can find him, we can solve this entire mystery."
"As soon as we finish our coffee," suggested Donald, "let's get busy and find him. He can't be far."
"That's right," said Adrian. "We'll round him up in short order. Hey, Billie?"
"We ought to; but I'll tell you what. You fellows go out and see if you can get a line on him, and I'll hang round the house to see that the devil doesn't come and steal the rest of the house."
"Especially Lucia," laughed Donald.
"That's all right," was the good-natured reply; "but I have an idea that the devil and Strong may have something in common."
"You don't think it was Strong who came and took the box, do you?" queried Adrian.
"I don't know just what I do think, Ad; butI'm going to do a little detective work and I want to give the impression that we are all out. When you fellows go out, don't say anything that would cause any one in hiding to think we are not all going out together. Do you sabe?"
"Sure. I hope you'll get a clue if we do not."
When the others had gone, Billie sat quietly in his room for a long time. He could easily have gone to sleep, as he had had only a couple of hours' rest, but he made up his mind that he would not be caught napping again if anything should happen.
But nothing happened.
The minutes passed into hours and it was rapidly nearing noon when Billie made up his mind that it was a bad job.
"We had our chance at daylight," he muttered, "and now we will not get another. Whoever is after the box, has it and is not going to take any further chance of being caught."
He went out into the patio and looked up at the sun. It was almost in the zenith and the air was stifling.
"Any one would be a fool to go out at this time of day," he mused. "I wonder where the fellows are?"
He stepped back under the shade of the arcade that extended clear around the patio and threw himself onto a stone seat.
"Queer old place," he thought, "and a queer old seat."
He laid his hand on one of the carved arms andmechanically toyed with an eagle's head that formed one of the decorations. To his surprise the head turned in his hand.
"I hope I haven't broken it," he said as he examined it more closely.
It was clearly made to revolve and so he turned it clear around, when of a sudden the arm of the seat fell apart and the bottom collapsed, disclosing to Billie's astonished eyes a pair of stairs.
Almost thrown to the pavement by the giving way of the seat, Billie picked himself up and looked about to see if he were observed.
There was no one in sight and he stooped down and examined the stairs carefully. Then he straightened up and rubbed his chin as a sudden gleam of intelligence passed through his brain.
"So," he muttered, "this is why Santiago dwells in a house that is directly back of the banker's. That was his box and he is the strange man who made the million-dollar deposit in Don Esteban's bank."
Then he stopped and pondered.
"But who stole the box? Not Santiago, for he has not left his room for days. If it was Strong, he must have entered the bank from some direction other than this. I don't understand, but I'm going to make some further investigation."
He reëntered his room, buckled on his automatic and took from his suit case—which, by the way, hehad located at the railway station along with that of his companions after the occupation of the city by the marines—his electric torch. Then he went out and descended the stairs, which he discovered were twenty-four in number.
Reaching the bottom he found himself upon a landing some six or eight feet square, from the opposite side of which another flight of stairs ascended.
"I reckon I better see where they lead to," was his comment as he slowly began their ascent.
After going up eighteen stairs his head touched the floor above. He counted the remaining steps by the light of his torch and found that there were six more. This would make the floor over his head on an exact level with the floor of Santiago's house.
"It's just as I expected," he muttered. "If I can get through this floor, I shall find myself in Don Esteban's residence—somewhere. But just where? That's the question."
He pushed upon the stone above his head, but it refused to move. Then he held up his torch and examined the ceiling carefully. Whatever the method by which the stones could be moved, it was carefully concealed.
Much chagrined, Billie at length decided to retrace his steps and await the coming of his companions. He reached the landing and crossed over to the steps by which he had descended.
Glancing up, he uttered an exclamation of surprise,for there at the opening and peering down the stairs was Ambrosio, the ape.
With a cry of recognition the simian started to descend the stairs, but at a noise from above he hesitated and then sprang back and out of sight.
An instant later the opening was closed and Billie was left in the darkness, except for the light of his torch.
While Billie was making his discoveries Donald and Adrian had also been busy.
When they left the house, at Donald's suggestion, they went first to the bank and told Don Esteban about the disappearance of the box and what the maid had seen. He was much disappointed until it was explained to him that they also had another clue.
"We shall spend our time in the slums," said Donald, "while our chum keeps watch at the house. We feel sure that between us we shall solve the mystery."
"I hope so," was Don Esteban's response. "Do you think I might be able to see this man Santiago?"
"I'm afraid not, sir! The doctor wants him tosleep as long as he can. We will let you know later in the day."
Leaving Don Esteban, the boys started for the plaza, intending to play the part of sightseers and visit every place in which a mountebank might reasonably expect to go. They felt certain that Strong would keep away from the more aristocratic places.
Keeping their eyes open and ever on the alert, they wandered about the streets and into many public places, but up to eleven o'clock had made no discovery. Then they entered a cantina for breakfast, purposely choosing one that was little frequented by Americans.
Seating themselves at a table in one corner where they could see without being seen, the boys ordered a hearty breakfast and then turned their attention to the others in the place.
At the table nearest them were three men of ordinary appearance, busy with their meal. Beyond them was an American soldier, who seemed to have dropped in out of curiosity. He was paying very little attention to his meal, but was eyeing a young woman who was seated behind the cash counter.
On the other side of the room, and partially hidden from our boys by the cash counter, was another man, smoking, and evidently waiting for some one. He kept his eye on the door and every once in a while glanced nervously at his watch.
"Not much going on in here," said Donald in English.
"No; but we are a little early. There may bemore in before we finish our breakfast."
It was a true prediction, for within the next five minutes as many more persons entered and disposed themselves around the various tables. Then the boys' breakfast was served and for a few minutes they were more absorbed in the food than in the guests.
As Donald raised his eyes for a moment, however, he caught sight of a man talking to the one sitting back of the cash counter. They were evidently arguing about something in an undertone and a minute later the newcomer took a seat with his back to the boys.
"Look!" was Donald's smothered exclamation, "over there by the cashier. Isn't that our man?"
Adrian raised his eyes and gazed hard at the back of the man's head.
"I could tell better if he would remove his hat. It does look like him, but he has disguised himself some way."
"Sure," laughed Donald. "That's part of his trade; but I'm dead sure it is Strong."
"What had we better do?"
"I don't know. He'll recognize us the minute he sees us. If he is keeping away from us, he will leave. If he is not, he may come over and speak to us. There is no reason why he should not, so far as he knows."
"How would it do to make ourselves visible?"
"I hardly know." Then after a pause: "I'll tellyou what. As soon as we finish we'll go out, as though we did not see him, but we will be sure to make enough commotion to attract his attention. Then we'll station ourselves where we can see him as he comes out."
"That's all right, Don; but suppose he doesn't come out?"
Donald scratched his head.
"Oh!" he exclaimed, "I knew I had a thought back of that. When he sees us, if he is not trying to avoid us, he will speak to us. If he does not speak to us, we will know there is something wrong and take immediate steps to have him arrested."
"But he may escape."
"How can he?"
"I suppose he could go out through the kitchen if he had to," was the ready reply.
"Yes, I suppose he could. We must do better than that."
"I'll tell you," said Adrian. "I'll go over and speak to that soldier in English. If it is Strong, he will hear me and will involuntarily make some move. If he wants to make himself known, he will. If he does not do so, we will simply sit here till he goes out and then shadow him."
"That sounds good. Go over and say 'Howdy' to the soldier."
Adrian arose from his seat and stepped over to the soldier.
"Hello, partner!" was his somewhat noisy greeting."Won't you come over to our table?"
"Why, sure, neighbor! I was just thinking that I was getting mighty lonesome."
He arose from his chair and took a seat beside Donald, who had been observing Strong closely. There could be no doubt that he had been attracted by Adrian's voice, but he gave no intimation that he knew the boys.
"Glad to see you," said Donald, without taking his eyes from his man. "Won't you have another cup of coffee?"
"Bet your life, neighbor!" Then as he lighted a fresh cigarette: "Smoke?"
"Never learned!" laughed Donald. "Seems mighty funny down here, doesn't it?"
"Sure does; but you're just as well off without it. Live here?"
"No," replied Adrian; "we were on our way home and got stuck!"
"What's the matter?" asked the soldier, with much concern. "Out of coin?"
"We haven't much; but Gen. Funston has promised to find us passage home in a few days. Our friend saw him early this morning," this latter remark expressly for Strong's ears.
"If he told you he'd do it, he will," said the soldier. "You can bet on him every time."
It was very evident from Strong's actions that he was taking in every word of the conversation,which was in English and in an unusually loud voice. He pretended to eat, then leaned over and said something to his companion, and a minute later arose from the table and hastily quitted the place.
But the boys were not to be fooled. They sprang from the table and hastily followed, Donald throwing a greenback to the cashier which more than doubly paid the bill.
Their sudden action did not escape the soldier, who, attributing it to another cause, also hastily quitted the cantina.
As the boys emerged into the street, they saw Strong hastening away in the direction of the custom house.
"Going to lose himself in the crowd," said Donald. "Don't let him get out of your sight."
"What's the matter?" asked the soldier, running to catch up with the boys. "Ugly greasers?"
"No," replied Donald, "we're shadowing a man who is wanted by Gen. Funston. That's him," pointing; "keep your eye on him."
"I thought you chaps had something on," laughed the soldier. "You can bet on me!"
Now that they approached nearer the center of the business portion of the city, there were more people on the street; but they were so near their quarry that they easily kept him in sight. Only once had he glanced back, but that was enough to convince him that he was followed.
"He's headed for somewhere," said Adrian. "Hedoesn't expect to get away from us simply by walking."
"Right," agreed Donald. "There he goes into the post office."
"Yes," from Adrian, "and it has two doors. You stop at the first one and I'll run to the other."
He started on a run and the soldier followed suit.
The sight of a man running and a soldier following, quickly attracted attention and pedestrians began to stop and see what the matter might be. In less than a minute a crowd had collected, among them several soldiers, who quickly brought Adrian to a halt.
"What's the matter?" asked one. Then as the soldier came up: "What are you chasing him for?"
"I'm not chasing him," laughed the seeming pursuer. "He and I are after another chap."
The delay occasioned by this interference was not great, but it was sufficient to allow Strong to escape, had it not been for Donald. He had seen the crowd gathering and, realizing what would happen, ran around the other way, just in time to see Strong disappearing around the corner of the street on which the bank was located.
Madly he dashed down the street and turned the corner in time to see Strong enter the big gate leading into the patio of Don Esteban's residence.
Putting on more steam, a couple of minutes laterDonald also dashed into the patio; but Strong was nowhere to be seen.
"He must be in the bank," muttered the boy, and he quickly entered the door.
But Strong had disappeared as completely as though the earth had opened and swallowed him up.
When the opening at the head of the stairs had closed upon Billie and he realized that he was shut in a subterranean passage, for a minute his heart sank within him.
He had tried to find an opening at the top of the opposite stairs and had failed, and he did not know that he would have any better success in trying to find a way to open the place through which he had descended.
"Nobody on earth knows that I am down here," he thought, "and with Santiago sick and maybe dying, no one on earth probably knows that there is such a passage."
But Billie was not the lad to sit down and cry. He had been in tight places before and he had an abiding faith in his own ability to do things. Therefore, he called up his courage and slowly mounted the stairs leading to Santiago's patio.
At the top of the stairs he found himself confrontedby exactly the same condition as he had found on the opposite side.
"But there is this difference," muttered Billie. "I know that there must be some sort of a crack where that slab fell back."
He held the electric bull's-eye close to the stone and scrutinized every spot.
Not a single crack could he spy.
Then he took out his big jack-knife and prodded with it clear across the width of the stairway.
There was nothing but solid stone.
"Looks kind o' desperate," he told himself, "but I have simply got to find an opening."
Again he prodded the place over without result.
"It's no use," he finally said to himself. "If I am to get out of here, help will have to come from somewhere outside. But how can it?"
He sat down on the stairs and thought deeply.
"If it is as I think," he mused, "these stairs have been used recently. The very fact that Ambrosio is prowling around here is proof that Strong must have been here at some time. But where is Strong?"
He slid down several steps and threw the light of his torch across to the opposite stairs.
"Bang!" went something that sounded like a falling stone.
Billie sprang to his feet.
"Click! Bang!" and down the opposite stairwaystreamed a ray of light.
Billie shut off his electric torch and waited.
Then on the steps there appeared a foot, then another, until a whole human body was in sight. Then "click, snap!" and the light disappeared.
"By George!" exclaimed Billie under his breath, "there's a man on the stairs right opposite to me. Who on earth can it be?"
His first inclination was to turn on the light, but on second thought he decided not to.
"I'll let him set the copy," thought Billie. "It's a mighty good thing to be able to spring the surprise."
He drew his automatic and stood ready for any emergency.
It was still as a tomb.
He could hear his own heart beat and he could also hear the heavy breathing of the other man.
"Sounds like he had been running and was just catching his breath," was Billie's mental comment.
After some minutes the man's breathing became more quiet and Billie heard him slowly descending the stairs.
"This won't do," thought Billie. "He probably has some kind of a light, and if he gets on the landing and I'm up here, I'll be like a man up a tree."
The lad sat down and slowly slid toward the bottom.
Being only a few steps from the landing, Billiewas down first. He crowded to the right and listened.
The other was now nearly on the landing. Now he was on the landing, hugging the wall on the side opposite Billie. Now they passed each other, or rather the man passed Billie, for Billie stood perfectly still.
It seemed as though he must hear Billie's breathing, but if he heard anything he must have thought it his own echo, never dreaming that he was not alone in the passage.
Now Billie could hear him ascending the stairs leading to Santiago's house, and his hope rose high.
"He must know how to open the floor," thought Billie. "I'll be right there when he does."
Silently as a cat Billie crept up the stairs behind his unknown companion.
Near the top the man stopped and a minute later he flashed an electric light against the stone overhead. Another minute and he heaved with the top of his head and the slab slid back.
"And now," exclaimed Billie in a deep voice, "put your hands over your head!"
Whether from fear or from the unparalleled surprise caused by hearing a human voice at such a time and in such a place, instead of obeying Billie's command, Strong's hands—for Strong it was—fell limp at his side and his electric torch fell to the stones beneath his feet.
"All right," continued Billy, "if that's the wayyou feel about it; but just remember that a single false move and I'll cut this automatic loose among your ribs. Now climb out a step at a time."
With face as white as marble at the shock he had just sustained, Strong obeyed implicitly and Billie was soon standing on the stone patio, looking Strong in the face.
"You're a good one, you are," he said sarcastically. "I should think you'd be ashamed to call yourself an American."
"What do you mean?" asked Strong in a trembling voice.
"Why, first of all, stealing from the bank, and then selling your own countrymen to the Mexicans."
"Who have I sold?"
"Do you mean to say that you didn't sell Gen. Funston to the greasers for ten thousand dollars?"
"Of course I do!" in a somewhat stronger voice.
"Perhaps you'll deny that you are Strong, the mountebank. You don't think for one minute that I don't know you in spite of your make-up, do you?"
"No, I'll admit that I'm the mountebank. As for my name that is of small importance in a country like this. But I did not sell Gen. Funston, as you put it. I knew the man I pointed out was not Funston and I knew that as soon as the Mexicans found it out they would let him go. Some onemight have told them rightly. As it was I spoiled their game and I got the money. Do you think it any crime to do that?"
"That's a matter I am not in a position to discuss," was Billie's answer. "But how about robbing the bank?"
"I had as much right to the box as any one."
"You'll have to prove that to some one besides me; all I can do is to turn you over to the authorities."
"Never!" cried Strong. "I'll die before I'll rot in a Mexican jail!"
He uttered a peculiar noise and before Billie could imagine what it meant, he felt himself seized from behind by a pair of hairy hands.
He had been in that clutch once before and recognized in an instant that he was in the grip of the ape.
He gave one loud cry for help and then turned loose with his automatic.
The tumult which followed is beyond description. Billie's shout was as nothing compared to the cry of the ape as one of the bullets struck him in the leg and another pierced his foot. Loosing his hold upon the lad, he grabbed for the weapon, but Billie managed to evade him and would undoubtedly have slain the animal had not Strong sprung to his assistance, with the result that in another minute Billie was disarmed.
Ill would the lad have fared then, at the handsof his two assailants, had not the noise attracted to the scene several soldiers, while an instant later came a loud shout as Donald and Adrian dashed into the patio.
On the other side of the square they had heard Billie's shout, followed by the automatic, and had rushed to his aid.
In another minute both Strong and his hairy friend were overcome and securely bound.
"Where did you find him?" asked Donald, pointing to Strong.
"Down there," was Billie's reply, as he pointed toward the still open underground passage way.
"How did he get there?"
"I suppose he entered from a similar entrance in Don Esteban's patio. I have had an idea all the time that there was some reason for the position of these two houses."
"But it doesn't lead into the bank. How could he steal the box out of the vault?"
"There is the real thief!" exclaimed Billie, pointing to the ape. "He sneaked in while Strong kept the bank employés engaged. By some mistake in his understanding he put the envelope back in the bank the next day instead of putting back the box. It was he who crawled through the bars into Santiago's library. He was also the devil who scared the maid almost into fits."
"Well! Well!" exclaimed a voice from the gateway. "I never could have believed it."
The voice was that of Don Esteban, who hadentered while Billie was speaking.
"I have come to see this strange man, Santiago Ojeda," he explained. "What says the doctor?"
"Here comes the doctor now," announced Adrian as the physician made his appearance in the gateway. "He can speak for himself."