ContentsINTRODUCTIONCHAPTER I. THE WAR TERRORCHAPTER II. THE ELECTRO-MAGNETIC GUNCHAPTER III. THE MURDER SYNDICATECHAPTER IV. THE AIR PIRATECHAPTER V. THE ULTRA-VIOLET RAYCHAPTER VI. THE TRIPLE MIRRORCHAPTER VII. THE WIRELESS WIRETAPPERSCHAPTER VIII. THE HOUSEBOAT MYSTERYCHAPTER IX. THE RADIO DETECTIVECHAPTER X. THE CURIO SHOPCHAPTER XI. THE “PILLAR OF DEATH”CHAPTER XII. THE ARROW POISONCHAPTER XIII. THE RADIUM ROBBERCHAPTER XIV. THE SPINTHARISCOPECHAPTER XV. THE ASPHYXIATING SAFECHAPTER XVI. THE DEAD LINECHAPTER XVII. THE PASTE REPLICACHAPTER XVIII. THE BURGLAR’S MICROPHONECHAPTER XIX. THE GERM LETTERCHAPTER XX. THE ARTIFICIAL KIDNEYCHAPTER XXI. THE POISON BRACELETCHAPTER XXII. THE DEVIL WORSHIPERSCHAPTER XXIII. THE PSYCHIC CURSECHAPTER XXIV. THE SERPENT’S TOOTHCHAPTER XXV. THE “HAPPY DUST”CHAPTER XXVI. THE BINET TESTCHAPTER XXVII. THE LIE DETECTORCHAPTER XXVIII. THE FAMILY SKELETONCHAPTER XXIX. THE LEAD POISONERCHAPTER XXX. THE ELECTROLYTIC MURDERCHAPTER XXXI. THE EUGENIC BRIDECHAPTER XXXII. THE GERM PLASMCHAPTER XXXIII. THE SEX CONTROLCHAPTER XXXIV. THE BILLIONAIRE BABYCHAPTER XXXV. THE PSYCHANALYSISCHAPTER XXXVI. THE ENDS OF JUSTICE