The Case of the Black Twenty-Two by Brian Flynn

Anthony took out his pocket-knife and carefully extracted the bullet from its paper bed. "I think that Goodall will have little difficulty in fitting this to Stewart's own revolver," he declared. He turned to Peter. "It's easier to piece the affair together now. When the burglar-the murderer if you prefer to call him so-cut across the room to put out the light he was holding this book in his hand-_so_. " He placed the fingers of his left hand on the switch and held the book in his right-with the back of the cover facing the door. Peter nodded-the scene was now becoming plainer to him, and its visualization most intriguing. "Stewart entered in the dark as I told you-and challenged the person he knew was facing him. At first he got no reply, but the intruder _attempted to replace the book on its shelf in the bookcase at his side_-he was familiar with its location because he had replaced it _on many occasions before_. Stewart detected the movement and instantly fired _in the direction of the sound_. Then the gentleman concerned so closely with historical research considered his safest plan was to disclose his identity-it might save his life for one thing. You know the result!"

"Wonderful-Bathurst! " said Peter. "I can see the whole thing as you depict it-there isn't a weak link in your chain."