“I will add whatever is necessary, too,” put in Warrington, eagerly.  “I can stand the loss of the car—­in fact, I don’t care whether I ever get it back.  I have others.  But I can’t stand the thought that my car is going about the country as the property of a gunman, perhaps—­an engine of murder and destruction.”

Garrick had been thoughtfully balancing the exploded shell between his fingers during most of the interview.  As Warrington concluded, he looked up.

“I’ll take the case,” he said simply.  “I think you’ll find that there is more to it than even you suspect.  Before we get through, I shall get a conviction on that empty shell, too.  If there is a gunman back of it all, he is no ordinary fellow, but a scientific gunman, far ahead of anything of which you dream.  No, don’t thank me for taking the case.  My thanks are to you for putting it in my way.”

CHAPTER III

THE MYSTERY OF THE THICKET

“You know my ideas on modern detective work,” Garrick remarked to me, reflectively, when they had gone.

I nodded assent, for we had often discussed the subject.

“There must be something new in order to catch criminals, nowadays,” he pursued.  “The old methods are all right—­as far as they go.  But while we have been using them, criminals have kept pace with modern science.”

I had met Garrick several months before on the return trip from abroad, and had found in him a companion spirit.

For some years I had been editing a paper which I called “The Scientific World,” and it had taxed my health to the point where my physician had told me that I must rest, or at least combine pleasure with business.  Thus I had taken the voyage across the ocean to attend the International Electrical Congress in London, and had unexpectedly been thrown in with Guy Garrick, who later seemed destined to play such an important part in my life.

Garrick was a detective, young, university bred, of good family, alert, and an interesting personality to me.  He had travelled much, especially in London, Paris, Berlin, and Vienna, where he had studied the amazing growth abroad of the new criminal science.

Already I knew something, by hearsay, of the men he had seen, Gross, Lacassagne, Reiss, and the now immortal Bertillon.  Our acquaintance, therefore, had rapidly ripened into friendship, and on our return, I had formed a habit of dropping in frequently on him of an evening, as I had this night, to smoke a pipe or two and talk over matters of common interest in his profession.

He had paused a moment in what he was saying, but now resumed, less reflectively, “Fortunately, Marshall, the crime-hunters have gone ahead faster than the criminals.  Now, it’s my job to catch criminals.  Yours, it seems to me, is to show people how they can never hope to beat the modern scientific detective.  Let’s strike a bargain.”