Shortly afterward the butler knocked at the study door and opened it.

“Mr. Chester J. Gillespie to see you, sir,” he announced.

Before Nick could reply, or the butler could get out of the way, for that matter, the young man named pushed into the room, his face pale with agitation.

“You must help me, Mr. Carter!” he cried excitedly. “I——”

He paused as Nick motioned the butler to withdraw and close the door. When the servant had complied, Nick said quietly:

“Sit down, Mr. Gillespie. I’m very sorry to learn that some one has attempted to blackmail you, but there’s no necessity for such great haste.”

His caller had started to take a chair, but paused with his hand on the back of it, and stared at Nick in the greatest amazement. Presently, a spot of angry red appeared in each pale cheek, and his rather weak jaw thrust out aggressively.

“By Heaven!” he breathed. “I believe you are in league with the fellow. I’ll swear I do! How otherwise could you know that——”

“That will be about enough of that, Gillespie!” the detective said sternly. He had heard too many such accusations in the last few hours. “If you have come to me for help, as your rather abrupt opening words would seem to indicate, let me warn you that you are not furthering your case by insulting me.”

“I—I beg your pardon, Mr. Carter,” the bewildered young man stammered. “I didn’t mean it, of course, but you are positively uncanny, and I could not understand how——”

“It’s very simple, though,” Nick told him. “I’ve been robbed of some papers, unfortunately, and those dealing with your case are among them. Naturally, therefore, when you rushed in in that fashion, I concluded that the thief had tried to bleed you.”

“Oh! So that was it?” Gillespie murmured somewhat sheepishly. Again his anger and sense of injury got the upper hand. “Then it’s you I have to thank for this, after all!” he cried. “I supposed my secret safe with you, as safe as if it were buried with me. Now, you calmly announce that it has been stolen from you. This is too much, Carter! Can’t you keep your papers where they will be safe? What right have you got to preserve such records, anyway? Why don’t you destroy them for the sake of your clients? It’s unbearable! This will be the ruin of me! If Florence finds out about it, she will refuse to marry me, and——”

The detective held up his hand commandingly, and the young man—he did not appear to be over twenty-five—lapsed into silence.

“I have already told you, Gillespie, that I profoundly regret what has happened. You are forgetting yourself, though, and wasting time. I already know who made away with those papers, and, with your assistance, I hope to lay a trap for him that will bring his schemes to an end very quickly. I think I can promise you that there will be no publicity, and that nothing need interfere with your approaching marriage. Now, tell me precisely what has happened.”

Young Gillespie was several times a millionaire, having inherited a large fortune from his father a year or two before. The responsibility thus imposed upon him had sobered him down in a remarkable manner, and he was looked upon in certain quarters as one of the coming leaders in the financial world. Before his father’s death, however, he had sown a lot of wild oats of one sort or another, and it was in connection with one of these youthful escapades that Nick had been called in about four years previously.

The affair threatened to be very serious, for the time, but the detective’s skill had been brought to bear in a surprising manner, with the result that everything had been smoothed out as well as possible without the vaguest rumor having got abroad.

The young man fumbled in his pocket with a gloved hand, and produced a sheet of notepaper, the top of which had obviously been cut away.

“That was found under the door when the house was opened up this morning,” he said. “Here’s the envelope. It was not stamped, of course.”

Nick smoothed out the sheet of paper and looked at the sprawling, uncertain writing that covered it. He read:

“I know all about the affair of four years ago. My price for silence is one hundred thousand dollars. Have it ready when I call, or pay it to any one who may present an order from me. Don’t think you can stop this by trying to have me arrested. You will fail, and the whole story will come out. I have fully arranged for its publication, no matter what happens to me. The money is the only thing that will buy my silence. Pay it, and your secret is safe. What is more, you will never hear from me again. Refuse to pay it, and—ruin!”

It was a bold letter, but Nick saw that it was nothing but a bluff. He said as much.

“I hope you haven’t been deceived by this,” he remarked, tapping the sheet. “This fellow is working alone, you may be sure, and, therefore, it isn’t at all likely that he has ‘arranged’ anything of the sort in case he should be arrested. By this, as you ought to know, the newspapers would not publish a story about you without warning. You have too much money and too many friends. You would have an opportunity to bring your influence to bear, and the story would be killed.”

“That sounds plausible enough,” Gillespie admitted. “That’s what I would tell any one else in my position, if he were similarly threatened. When this sort of thing comes home to a fellow, though, it makes a lot of difference.”

“I know,” the detective replied, with a nod. “That’s the sort of mood such a scoundrel counts on.”

He paused and thoughtfully fingered the letter.

“I must confess that this is a disappointment,” he resumed slowly. “I had hoped that the blackmailer would set a definite time for his call, or ask you to take the money to some specified place. This, however, avoids anything of that sort, and leaves me nothing definite to go on. All it tells us is that he expects to call at some unnamed hour—perhaps to-day, perhaps to-morrow, perhaps not for several days. I think we need not bother about the hint that he may send some one with a written order, for if such a person presented himself, I feel sure it would be the blackmailer, and no other. This absence of details, however, makes it rather difficult to know just what to do.”

“How would this do?” Gillespie said hesitatingly. “You are a genius at make-up. Why don’t you pass yourself off for me? Go to my place on Fifth Avenue and wait for this fellow, whoever he is, to call? The chances are that he won’t put it off very long, and even if you had to remain there a couple of days, you would not mind, would you, if you could nab your man at the end of your wait?”