“I am absolutely sure,” Nick declared, “that if I brought you into court, you would spend the next half a dozen years in jail. There is no reason why I should let you go free, except that I believe you could be a wonderfully brilliant man and a good citizen if you liked. I am going to give you that chance. You are free to go—no, no, don’t make any protestations. Get out of here as quick as you like and become an honest man. Let me warn you, however, that if I ever catch you engaged in any crooked work again, I will see that your due punishment is meted out. Now go.”

The man slunk away with a hunted expression in his eyes.

Little did Nick guess that within a very little while he would be on the track of Lannigan again.

He was sitting at breakfast one morning, when the first mail arrived, bringing with it the following singular letter, unsigned:

“‘You are a friend of Sanborn. I’ll give you a tip. His daughter is to be married. The presents will be many and of value, and, on the day of the wedding, the house will be raided. A word to you is sufficient.’”

Nick carefully read the letter, even studied it, and the paper on which it was written. But he gained nothing from such examination.

A close inspection of the envelope showed that it had been deposited in the general post office before six o’clock on the previous evening.

While the letter did not specify which Sanborn it was, and while a hundred of that name, perhaps, were to be found in the directory, Nick had no doubt that Harmon Sanborn was the one meant.

Harmon Sanborn was a very rich man, worth many millions, and in very active business life. The relations between this multi-millionaire and the famous detective were close, having been begun several years before when Nick was retained to trace a peculiar defalcation occurring in one of the many business enterprises of Sanborn.

Nick knew that Mr. Sanborn had more than one daughter unmarried, but he had not heard that the wedding of one was about to take place, as his anonymous letter indicated.