Still deep in thought, Inspector Whyland left the picture-house and walked slowly back to the police station through the less frequented streets. It was a little past eight on a typical December evening, with a light wet mist which magnified the outlines of the passers-by and covered the pavements with a shining dampness. But the weather never had much effect upon Whyland, and, beyond a passing reflection that on such an evening murder in the streets of London was not, after all, an enterprise presenting any great difficulties to a determined man, he paid no great attention to it. He reached the police station without adventure, ordered a modest supper, and sat down to deal with the mass of reports which awaited him. He was thus engaged when a sergeant entered the room, with the message that a man giving the name of Copperdock wished to speak to him on the telephone. He rose, walked to the instrument, and picked up the receiver. “Inspector Whyland speaking,” he said coldly. “Is that you, Inspector?” came an excited voice, which Whyland recognized at once. “Can you come and see me at once? I’ve something very important to tell you.” Whyland hesitated for a moment. Whatever it was that Mr. Copperdock had to say to him, a visit to his house could afford him an excellent opportunity for keeping his eyes open for some clue in support of his theory. “Yes, I’ll come along straight away,” he replied. With a word to the sergeant, he left the station and walked rapidly to Praed Street. It was about a quarter to ten when he arrived and rang the bell outside Mr. Copperdock’s shop. The tobacconist was obviously awaiting him, and the door was opened immediately. With a brief word of greeting, Mr. Copperdock led the way upstairs to the sitting-room. Then, shutting the door carefully behind him, he turned dramatically, “I’ve seen that there black sailor!” he exclaimed in a hoarse whisper. Inspector Whyland looked at him sharply. When the reward had originally been offered, he had been overwhelmed by a flood of people who had claimed to have seen the “black sailor,” but of late this elusive figure had ceased to occupy the popular imagination. Was this a vindication of his theory, showing that Mr. Copperdock’s brain was completely under the influence of the crime? “You have seen the black sailor? Sit down and tell me all about it, Mr. Copperdock,” he replied gravely. But Mr. Copperdock was far too excited to sit down. “I see him plain as I see you now,” he exclaimed. “Just after I left the Cambridge Arms——” But Inspector Whyland put out his hand and forced him gently into the nearest chair. “Now, look here, Mr. Copperdock, if your information is to be of any use to me, you must tell it to me in the proper order. Begin by telling me how you spent the evening.”