The irony brought some colour to his cheek. "My neck is in no danger," he retorted angrily. "What can you prove against us you fool, except that I performed a wonderful operation in the cause of science, in the ardent hope of saving a man's life, and in the sure trust of benefitting the whole human race?" "But the man died, doctor, and he was one of nineteen! The coroner will shortly have a harvest, nineteen autopsies, Sir Charles! Think of them! Nineteen autopsies!" "You fool," he repeated in tones of repressed passion, "if there were even ninety--what of it? But enough of this! choose between five hundred pounds and the lock-up. Choose quickly!" He turned as he spoke and strode to the door. His hand was already on the latch. In another second the door would have been thrown wide. Perhaps there was a policeman in the passage, I thought it unlikely but still--possible! At all events it was time for me to cease trifling with my adversary. "You appear, Sir Charles Venner, to have forgotten the matter of Cavanagh's death!" I hissed out. "He killed himself at the hospital, and his body was discovered at the studio!" "That can be explained!" he retorted; but his hand fell softly from the latch. "We have plenty of witnesses who saw his suicide." "Suicide!" I sneered. "What _of rule three, you one of seven murderers_!" Sir Charles Venner re-crossed the room and quietly resumed his chair. His face was still as expressionless as a mask, but all the lustre had departed from his eyes. "What do you know of rule three?" he asked in lifeless tones after a long intense pause. I knew so little that it seemed necessary to lie. "Enough to hang you," I murmured, smiling pleasantly. "I should tell you perhaps, my dear Sir Charles, that I have impersonated Sir William Dagmar more often than I have fingers and toes--during the past twelve months. Ha! you start!" I laughed wickedly. "Did you really permit yourself to dream that you have guessed the full extent of my depredations on your order--from your one or two chance and predestined discoveries. Oh! oh! Ha! ha! This is really too good!" He bit his lips and eyed me sternly. "I shall need better proof than your word," he said. I nodded, got to my feet and strode to the door. I threw it open and with an elaborate bow pointed to the passage. "You shall have it," I cried, "but only in the police court!" "Bluff!" he sneered. "Bluff!" He did not move from his chair. "Oh!" said I, "you choose to pay yourself a compliment! So you think I would follow your example of a moment since? But you are wrong!" I walked to the electric bell and pressed the button. Sir Charles Venner's impassivity disappeared like magic. His face turned scarlet and he sprang instantly afoot. "Curse you!" he grated out, "what would you do?" "Sir, our interview is at an end. My servant will show you to the street!" "The sum you ask is utterly beyond our means!" I shrugged my shoulders. "Five thousand!" he hissed. I yawned.