"Not only one, but two," Preston declared, "as you've seen for yourself. See that black mark, like an inverted V, upon the head? That's characteristic of the cobra family, and this specimen--common to the veldts of South Africa where he is known as the 'sheep stinger'--is first cousin to the big king cobras. Montgomery's former partner evidently brought him over from Africa with this idea in mind. But when he was packing him in the box--the airhole in the end of it gave me the first inkling, by the way--he got careless and the snake bit him. Only medical attention saved his life until this afternoon, else he'd have passed along before Montgomery. I think that closes the case, Chief, and in spite of the fact that the mails were used for a distinctly illegal purpose, I believe your department ought to handle the matter--not mine." "But the trap--the milk? How'd you happen to hit on that?" "When you told me what the special-delivery man said about the contents of the package 'wabbling' I figured that the box must have contained a snake," explained the Postal operative. "An animal would have made some noise, while a snake, if well fed, will lie silent for hours at a time. The constant motion, however, would have made it irritable--so that it struck the moment Montgomery removed the lid of the box. That explains the wound in his hand. He knew his danger and deliberately fired, hoping to cauterize the wound and drive out the poison. It was too quick for him, though, or possibly the shock stunned him so that he fell. "Then, in spite of the fact that your men claimed to have searched the room thoroughly, that noise in the corner warned me that whatever killed Montgomery was still here. Going on the theory that the majority of snakes are fond of milk, I rigged up the trap. And there you are!" * * * * * "Yes," concluded Quinn, "the majority of the cases handled by government detectives have to do with counterfeiting or smuggling or other crimes against the federal law--offenses which ought to be exciting but which are generally dull and prosaic. Every now and then, though, they stumble across a real honest-to-goodness thrill, a story that's worth the telling. "I've got to be away for the next couple of months or so, but drop around when I get back and I'll see if I can't recall some more of the problems that have been solved by one of the greatest, though least known, detective agencies on the face of the earth." THE END * * * * * Transcriber's Notes: Contents page changes made to agree with chapter headings: "Lost--$100,000!"--quotes and exclamation point added. "The Double Code"--quotes added. "Thirty Thousand," and again on P. 253--hyphen removed (more frequent without). After Contents page, "On Secret Service" displays twice--once alone on a page, and again above the Chapter I heading. One of the redundancies has been deleted.