INTRODUCTION
I. THE WAR TERROR
II. THE ELECTRO-MAGNETIC GUN
III. THE MURDER SYNDICATE
IV. THE AIR PIRATE
V. THE ULTRA-VIOLET RAY
VI. THE TRIPLE MIRROR
VII. THE WIRELESS WIRETAPPERS
VIII. THE HOUSEBOAT MYSTERY
IX. THE RADIO DETECTIVE
X. THE CURIO SHOP
XI. THE "PILLAR OF DEATH"
XII. THE ARROW POISON
XIII. THE RADIUM ROBBER
XIV. THE SPINTHARISCOPE
XV. THE ASPHYXIATING SAFE
XVI. THE DEAD LINE
XVII. THE PASTE REPLICA
XVIII. THE BURGLAR'S MICROPHONE
XIX. THE GERM LETTER
XX. THE ARTIFICIAL KIDNEY
XXI. THE POISON BRACELET
XXII. THE DEVIL WORSHIPERS
XXIII. THE PSYCHIC CURSE
XXIV. THE SERPENT'S TOOTH
XXV. THE "HAPPY DUST"
XXVI. THE BINET TEST
XXVII. THE LIE DETECTOR
XXVIII. THE FAMILY SKELETON
XXIX. THE LEAD POISONER
XXX. THE ELECTROLYTIC MURDER
XXXI. THE EUGENIC BRIDE
XXXII. THE GERM PLASM
XXXIII. THE SEX CONTROL
XXXIV. THE BILLIONAIRE BABY
XXXV. THE PSYCHANALYSIS
XXXVI. THE ENDS OF JUSTICE

INTRODUCTION

As I look back now on the sensational events of the past months since the great European War began, it seems to me as if there had never been a period in Craig Kennedy's life more replete with thrilling adventures than this.

In fact, scarcely had one mysterious event been straightened out from the tangled skein, when another, even more baffling, crowded on its very heels.

As was to have been expected with us in America, not all of these remarkable experiences grew either directly or indirectly out of the war, but there were several that did, and they proved to be only the beginning of a succession of events which kept me busy chronicling for the Star the exploits of my capable and versatile friend.

Altogether, this period of the war was, I am sure, quite the most exciting of the many series of episodes through which Craig has been called upon to go. Yet he seemed to meet each situation as it arose with a fresh mind, which was amazing even to me who have known him so long and so intimately.

As was naturally to be supposed, also, at such a time, it was not long before Craig found himself entangled in the marvelous spy system of the warring European nations. These systems revealed their devious and dark ways, ramifying as they did tentacle-like even across the ocean in their efforts to gain their ends in neutral America. Not only so, but, as I shall some day endeavor to show later, when the ban of silence imposed by neutrality is raised after the war, many of the horrors of the war were brought home intimately to us.

I have, after mature consideration, decided that even at present nothing but good can come from the publication at least of some part of the strange series of adventures through which Kennedy and I have just gone, especially those which might, if we had not succeeded, have caused most important changes in current history. As for the other adventures, no question can be raised about the propriety of their publication.

At any rate, it came about that early in August, when the war cloud was just beginning to loom blackest, Kennedy was unexpectedly called into one of the strangest, most dangerous situations in which his peculiar and perilous profession had ever involved him.

CHAPTER I

THE WAR TERROR

"I must see Professor Kennedy--where is he?--I must see him, for God's sake!"