“Perhaps the shot was fired by the murderer after Stewart was dead,” volunteered Peter. “Why?” demanded Anthony immediately. “Why should the murderer fire a shot that for all he knew might awaken the whole house?” “Well—as a blind,” supplemented Peter somewhat feebly. “Don’t think so—it doesn’t fit,” said Anthony, in summary dismissal of the theory. “The shot is fired,” reflected Anthony, “by Stewart, who has—according to his dress at the moment—come down to the library from his bedroom in a hurry—why does he fire—he doesn’t seem to have been attacked _then_, but afterwards—as you said earlier, the treachery and the attack appear to come from inside his own ménage and yet he _fires_—why?” His eyes wandered round the room—intent and purposeful. “Also, my dear Daventry, if he fires, as I’m out to assert that he _did_—where’s the bullet—eh—tell me that?” He stood with his left hand caressing his chin. “Supposing he didn’t know—supposing he wasn’t sure—that’s certainly an idea—that would account for the pocketing of his revolver _subsequently_—a feeling of safety—of security that came to him—false as it eventually turned out to be—but yet conveyed to him temporarily by the conditions.” He came across to Peter full of this latest piece of theorizing. “Look here, Daventry—let’s remember what Colonel Leach-Fletcher told us. He was Stewart’s friend—his evidence should be reliable. He was insistent that Stewart was worried about something that was going on in his house. The word that Stewart used, according to the Colonel, imputed _treachery_ on the part of somebody here! Now do you remember what the Colonel went on to say? He stated that in his opinion Stewart had come to a decision ‘to take the bull by the horns’ in an attempt to put a stop to whatever was happening. Remember that?” Peter agreed. “Yes.” “Well now,” continued Anthony, “let’s assume that Stewart was thoroughly on the _qui vive_ that night, and succeeded in identifying this disturber of his peace. He comes hurriedly downstairs—armed—ready to defend himself if necessary—prepared to see the thing through to the bitter end—as he comes down”—he swung round on to Peter in violent enthusiasm—“I deserve to be kicked, Daventry, I’ve been painfully slow to appreciate what actually happened—but I think I’m clear now. Go and stand at the door, will you—just where you would be if you had just opened it and entered.” Peter stared wonderingly but obeyed him. Anthony went to the side of the bookcase and faced the opening door. “This is where the murderer stood,” he declared gravely, “when Stewart opened the door. He came here from that chair.” He indicated the chair by the desk—the chair in which the dead man had been discovered. “How do you know that?” demanded Peter.