Thank you for the medicine, doctor," he added loudly.

    Dick was not deceived by so transparent a bluff. He followed the doctor into the hall. Farther the strange man did not invite him.

    "You are police, yes?" he said, when Dick produced his card. "How extraordinary and bizarre! To me the police have not come for a long time—such trouble for a man because he experiments for science on a leetle dog! Such a fuss and nonsense! Now you ask me—what?"

    In a few words Dick explained his errand, and to his amazement the strange man answered immediately:

    "Yes, the book, I have it! It was on the shelf. I needed it, so I took it!"

    "But, my good man," said the staggered detective, "you're not allowed to walk off with other people's property because you want it!"

    "It is a library. It is for lending, is it not? I desired to borrow, so I took it with me. There was no concealment. I placed it under my arm, I lifted my hat to the young signora, and that was all. Now I have finished with it and it may go back. Haeckel is a fool; his conclusions are absurd, his theories extraordinary and bizarre." (Evidently this was a favourite phrase of his.) "To you they would seem very dull and commonplace, but to me—— " He shrugged his shoulders and uttered a little cackle of sound which Dick gathered was intended to be laughter.

    The detective delivered a little lecture on the systems of loaning libraries, and with the book under his arm went out to rejoin the waiting Mr Cawler. He had at least an excuse for returning to the library, he thought with satisfaction.

    "Now, Cawler"—he began without superfluous preliminaries and his voice was peremptory—"I want to know something about you. Is Stalletti a friend of yours?"

    "He's my doctor," said the man coolly.

    He had a merry blue eye, and he was one of the few people who had passed through his hands for whom Dick had a genuine liking. Tommy Cawler had been a notorious 'knocker-off* of motor-cars, and a 'knocker-off' is one who, finding an unattended machine, steps blithely into the driver's seat and is gone before the owner misses his machine. Tommy's two convictions had both been due to the unremitting inquiries of the man who now questioned him.

    "I've got a regular job; I'm chauffeur to Mr Bertram Cody," said Tom virtuously. "I'm that honest now, I wouldn't touch anything crook, not to save my life."

    "Where does Mr Cody live when he's at home?" asked Dick, unconvinced.

    "Weald House. It is only a mile from here; you can step over and ask if you like."

    "Does he know about your—sad past?" Dick questioned delicately.

    "He does; I told him everything. He says I am the best chauffeur he ever had."

    Dick examined the man carefully.

    "Is this er—er—uniform that your employer prefers?"

    "I'm going on holiday, to tell you the truth," said Mr Cawler. "The governor is pretty good about holidays. Here's the address if you want it."

    He took an envelope from his pocket addressed to himself 'c/o Bertram Cody, Esq., Weald House, South Weald, Sussex.'

    "They treat me like a lord," he said, not without truth. "And a more perfect lady and gentleman than Mr and Mrs Cody you'd never hope to see."

    "Fine," said the sceptical Richard. "Forgive these embarrassing questions. Tommy, but in my bright lexicon there is no such word as 'reform'."

    "I don't know your friend, but you've got it wrong," said Tommy hazily.

    Martin offered him a lift, but this was declined, and the detective went back alone to London, and, to his annoyance, arrived at the library half an hour after the girl had left.

    It was too late, he thought, to see Mr Havelock of Lincoln's Inn Fields, and in point of fact the recollection of that engagement brought with it a feeling of discomfort. His plans were already made. He intended spending a month in Germany before he returned to the work which he had promised himself: a volume on 'Thieves and Their Methods', which he thought would pleasantly occupy the next year.

    Dick, without being extremely wealthy, was in a very comfortable position. Sneed had spoken of a six-figure legacy, and was nearly right, although the figures were dollars, for his uncle had been a successful cattle fanner of Alberta. Mainly he was leaving the police force because he was nearing promotion, and felt it unfair to stand in the way of other men who were more in need of rank than himself. Police work amused him. It was his hobby and occupation, and he did not care to contemplate what life would be without that interest.

    He had turned to go into his flat when he heard a voice hail him, and he turned to see the man whom he had released that morning crossing the road in some haste. Ordinarily, Lew Pheeney was the coolest of men, but now he was almost incoherent.

    "Can I see you, Slick?" he asked, a quiver in his voice, which Dick did not remember having heard before.

    "Surely you can see me. Why? Is anything wrong?"

    "I don't know." The man looked up and down the street nervously.