A moment was sufficient to satisfy Patsy that he was disguised. Half an hour passed, during which Patsy begged, when he could without being discovered by policemen, and still shadowed the disguised man, who was watching the main entrance. Finally this man strolled away like one who did so reluctantly. Patsy watched him with a thrill of delight. He had found his man again. The man went to a hotel, where he sat down in the writing-room and, taking paper and envelope from his pocket, began to write letters. Patsy slipped away and made another change in his appearance, and, coming back, set out to write letters himself. When the other had written two letters, he got up and went out, followed by Patsy. This time he went to an American District Telegraph office, handing the letters in and paying the fee. Leaving the office he went directly back to the hotel where he had written his letters, and, calling for the key of room ninety-eight, said to the clerk: “I am tired and shall lie down for a nap. Call me by two o’clock. Not later.” He went to his room. Patsy turned over the register and found the name of Harold Stanton, and opposite the number ninety-eight. “How long has Stanton been staying with you?” asked Patsy. “Only since last night.” “What do you know of him?” “Nothing. He paid for his room for two nights. But he wasn’t in his room last night.” Patsy went away, saying: “What next? I’ve run him down to this place, and know he figures as Harold Stanton.” He went back to the American District Telegraph office and persuaded the man in charge to give him the names of the persons to whom Stanton had written letters. One was Nick Carter, the other was Alpheus Cary. Patsy gave a long whistle, and set out to find his chief. CHAPTER IV. THE REAL THING. After Nick had talked over the case with Chick and Ida, he had sent Chick to the house in Seventeenth Street to take stock of it and to make inquiries. “Chick,” he had said, “I don’t think you will learn much, for I fancy the house has been abandoned by these people. However, you may learn something in looking it up.” He then went to his house, to find a caller awaiting him. Nick looked at the card, but did not recognize the name. It was Richard F. Mountain. He sent for the caller to come to his own room. Mr. Mountain was one who showed in his movements that he was a man of business, and accustomed to affairs. “Are we alone, Mr. Carter?” he added, on entering. “What I have to say is strictly confidential.” “We cannot be overheard here,” replied Nick. “Then the next question is, can I rely upon you to take my case?” “I never decide to take a case until I hear the story,” said Nick, “but whatever confidence you give me will be respected.” “It’s a case of attempted blackmail,” replied Mr. Mountain. “The Brown Robin?” asked Nick. Mr. Mountain stared a moment before he replied: