“Well, sit down, and tell us all about it,” said the Professor, motioning Hanslet towards a comfortable chair. “You will relieve the tedium I am feeling at having nothing to do.” Hanslet sat down, and, as he did so, looked enquiringly at the Professor. “You say you’ve nothing to do, sir? Well, I’m very glad to hear that. The truth is that I didn’t come here to tell you my experiences. As a matter of fact, I meant to take a month’s leave when I got back, but the Chief asked me to wait a bit and take over a case which has been puzzling the Yard for several months. And I wanted to ask your advice, if you would be good enough to listen.” The Professor rubbed his hands together briskly. “Excellent, excellent!” he exclaimed. “I told you this morning, Harold, that a problem was bound to turn up before long. By all means tell me your difficulties, Inspector. But let me beg of you to keep to facts, and not to digress into conjecture.” Hanslet smiled. The Professor’s passion for facts was well-known to him from past experience. “Well, I expect you know as much about it as I do,” he began. “Ever since Tovey the greengrocer was killed last November, there’s been a lot in the papers——” But the Professor interrupted him. “I should perhaps have explained, Inspector, that since last October I have scarcely opened a newspaper. My whole mind has been concentrated upon a task which is now happily finished. The name of Tovey the greengrocer is, I regret to say, utterly unfamiliar to me. I should be glad if you would treat me as one who has only lately reached this world from the planet Mars, and give me the facts without presuming that I have any previous knowledge of them.” “Very well, Professor,” replied Hanslet. “You must have heard of a series of deaths under peculiar circumstances which have occurred in Praed Street, not half a mile away from here? Why, I read about them in New York! They caused a great sensation.” “I am not concerned with popular sensations,” said the Professor coldly. “I admit that some rumours of such happenings penetrated the isolation with which I have endeavoured to surround myself, but I dismissed them from my mind as likely to introduce a disturbing factor. I repeat that you had better repeat the facts, as briefly as possible.” “Very well, Professor, I will tell you the story exactly as it was told to me at the Yard,” replied Hanslet. “You will be able to see how much is fact and how much conjecture. As I was not on the spot myself, I cannot vouch for the details. Will that do?” The Professor nodded, and turned to Harold. “Make a note of the names and dates mentioned by Inspector Hanslet,” he said. “Now, Inspector, you may proceed.”