“A hard-boiled egg! But when I turned around – not ten minutes later! – the newspaper was directly on top of the box and the book was gone! Yet the egg and the candlestick were just where they had always been. So a week later I came back and bought another copy – just as your shopman says. I took it home. I put it on the mantelpiece with Cooper’s Dictionary of Practical Surgery and stood the teapot on top. But it so happened that when I made the tea I dislodged both books and they fell into the basket where the dirty washing is put. On Monday, Jack Boot – my servant – put the dirty linen into the basket. On Tuesday the washerwoman came to take the dirty linen away, but when the bedsheets were lifted away, Cooper’s Dictionary of Practical Surgery was there at the bottom of the basket but The History and Practice of English Magic was gone!”

These speeches, suggesting some slight eccentricities in the regulation of Mr Green’s household, seemed to offer hope of an explanation.

“Could you not have mistook the place where you put it?” offered Mr Shackleton.

“Perhaps the laundress took it away with your sheets?” suggested Mr Murray.

“No, no!” declared Mr Green.

“Could someone have borrowed it? Or moved it?” suggested Shackleton.

Mr Green looked amazed at this suggestion. “Who?” he demanded.

“I … I have no idea. Mrs Green? Your servant?”

“There is no Mrs Green! I live alone! Except for Jack Boot and Jack Boot cannot read!”

“A friend, then?”

Mr Green seemed about to deny that he had ever had any friends.

Mr Murray sighed. “Shackleton, give Mr Green another copy and his money for the second book.” To Mr Green he said, “I am glad you like it so well to buy another copy.”

“Like it!” cried Mr Green, more astonished than ever. “I have not the least idea whether I like it or not! I never had a chance to open it.”

After he had gone, Mr Murray lingered in the shop a while making jokes about linen-baskets and hard-boiled eggs, but Mr Shackleton (who was generally as fond of a joke as any one) refused to be entertained. He looked thoughtful and anxious and insisted several times that there was something queer going on.

Half an hour later Mr Murray was in his room upstairs gazing at his bookcase. He looked up and saw Shackleton.

“He is back,” said Shackleton.

“What?”

“Green. He has lost his book again. He had it in his right-hand pocket, but by the time he reached Great Pulteney-street it was gone. Of course I told him that London is full of thieves, but you must admit …”

“Yes, yes! Never mind that now!” interrupted Mr Murray. “My own copy is gone! Look! I put it here, between d’Israeli’s Flim-Flams and Miss Austen’s Emma. You can see the space where it stood. What is happening, Shackleton?”