"Time is precious now, Wigan," said the professor. "You might telephone to the station and ask if they have found the driver of the taxi. I want to know if this poor fellow is the man he drove to Melbury Avenue last evening, also whether it has always been a Wednesday when he has brought him into this neighborhood; and, of course, you must ask him any questions which may lead to the identification of the dead man. I don't suppose he will be able to help you much in that direction. You will find, I fancy, that the driver got tired of waiting for his fare last night and drove away." "Or took another fare--the murderer," I suggested. "I don't think so," said Quarles. "You might also ask the inspector at the station whether he is prepared to swear that the first voice he heard over the 'phone--the voice which said 'police'--was a woman's. What time does it grow dark now, constable?" "Early--half-past four, sir." "I'll go, Wigan. I want to think the matter out before dark. Seven o'clock to-night--meet me at the top of the road at that time, and somewhere close have half a dozen plain clothes men ready for a raid. Now that we know murder has been done, you couldn't suggest a house to raid, I suppose, constable." "I couldn't, sir." "Nor can I at present. Seven o'clock to-night, Wigan." The professor's manner, short, peremptory, self-sufficient, was at times calculated to disturb the serenity of an archangel. I had been on the point of quarreling with him more than once that morning, but the sudden demonstration of what seemed to be the wildest theory left me with nothing to say. Constable Baker had an idea of putting the case adequately, I think, when he remarked: "He ain't human, that's what he is." The taxi driver had been found, and, when taken to Hambledon Road, recognized the dead man as his fare. He had driven him to Melbury Avenue on four occasions, and each time it had been a Wednesday. Of course, the gentleman might have come more than four times, and on other days besides Wednesdays for all he knew. On each occasion he had been called off a rank in Trafalgar Square. His fare had paid him for the down journey before walking up the avenue, and had never kept him waiting so long before, so he gave up the job and went back to town. He had not picked up another fare until he got to Kensington. The inspector at the station was certain the message he had received was in a woman's voice, but he was not sure that the word "police" was in the same voice, or that it was a woman who spoke it. At seven o'clock I was waiting for Quarles at the top of Hambledon Road. He was punctual to the minute. "You've got the men, Wigan?" "They are hanging about in Melbury Avenue."