“That’s what I think,” exclaimed Anthony. “It seems to me that whoever was in here heard Stewart coming down from his bedroom and just had time to get over there and switch off the light. Stewart probably challenged from the doorway, and either at some movement on the part of the intruder or out of intense anxiety—he had been worrying, you know—he fired. Then I suggest that the burglar disclosed his identity deliberately to safeguard his own skin or that something happened that caused Stewart to discover it. That’s the reason, Daventry, why I say that we ought to find a bullet somewhere in here.” Peter grunted. “Might be in the burglar’s body for all you know!” “A thousand to one against that,” returned Anthony, as he came to the middle of the room. “It should be somewhere in the vicinity of that electric light switch,” he asserted. “The intruder would be standing there when Stewart fired.” But the wall was untouched—not a vestige of a scratch upon it anywhere. His eyes traveled to the bookcase. “What about the bookcase, Daventry?” “It’s sectional,” replied Peter, “and every section is protected by a glass shutter—no bullet can possibly have touched any of them—look for yourself—they’re all sound.” He motioned towards them with his hand. “Quite true,” said Anthony. “Then where the devil”—he paused for a second; “supposing one of the glass fronts was up—eh—what then?” “Then the bullet would hit the back of one of the books, of course.” “Supposing there were blank spaces—where books were missing from their places on the shelves?” Peter scratched his chin. “Then the bullet would go through the back of the bookcase—but it’s tremendous odds on a shot fired like this one was finding such a space as you describe—it would border on the miraculous.” Anthony nodded in acquiescence. “I agree.” Then he broke out again. “Damn it all, Daventry, I’m certain I’m right in my conclusion—that bullet must be somewhere about. Take down the books on the top shelves—that’s the nearest height, I should say, to where Stewart would have fired—and start with the top shelf nearest to the switch.” Peter somewhat reluctantly moved about three dozen volumes, tossing each one on to the floor as he did so. The woodwork at the back of the shelf was clean and unimpaired—no bullet had torn its destructive way through there. “Nothing here,” he declared over his shoulder to Anthony. But the latter was studying the books that Peter had just moved. One in particular seemed to be affording him particular interest. It was the thickest and bulkiest of them all. “Come here, Daventry, will you?” said Anthony. Peter strolled across. Anthony pointed to a hole neatly drilled in the back of the cover. He opened the book at a page near the beginning. “There’s our bullet—embedded in this book. The thickness of the paper and the size of the book—848 pages to be exact—were sufficient to arrest its further progress—it was the only possible solution that remained to us.”