He spoke with unconscious prescience. This was the key of the door of the vault. Removing his overall, Kerry laid it with his cane upon the scrap-heap, then he climbed down the ladder and found himself in the mouth of that low timbered tunnel, like a trenchwork, which owed its existence to the cunning craftsmanship of Sin Sin Wa. Stooping uncomfortably, he made his way along the passage until the massive door confronted him. He was in no doubt as to which key to employ; his mental condition was such that he was indifferent to the dangers which probably lay before him. The well-oiled lock operated smoothly. Kerry pushed the door open and stepped briskly into the vault. His movements, from the moment that he had opened the trap, had been swift and as nearly noiseless as the difficulties of the task had permitted. Nevertheless, they had not been so silent as to escape the attention of the preternaturally acute Sin Sin Wa. Kerry found the place occupied only by the aged Sam Tûk. A bright fire burned in the stove, and a ship’s lantern stood upon the counter. Dense chemical fumes rendered the air difficult to breathe; but the shelves, once laden with the largest illicit collection of drugs in London, were bare. Kerry’s fierce eyes moved right and left; his jaws worked automatically. Sam Tûk sat motionless, his hands concealed in his sleeves, bending decrepitly forward in his chair. Then: “Hi! Guy Fawkes!” rapped Kerry, striding forward. “Who’s been letting off fire-works?” Sam Tûk nodded senilely, but spoke not a word. Kerry stooped and stared into the heart of the fire. A dense coat of white ash lay upon the embers. He grasped the shoulder of the aged Chinaman, and pushed him back so that he could look into the bleared eyes behind the owlish spectacles. “Been cleaning up the ‘evidence,’ eh?” he shouted. “This joint stinks of opium and a score of other dopes. Where are the gang?” He shook the yielding, ancient frame. “Where’s the smart with one eye?” But Sam Tûk merely nodded, and as Kerry released his hold sank forward again, nodding incessantly. “H’m, you’re a hard case,” said the Chief Inspector. “A couple of witnesses like you and the jury would retire to Bedlam!” He stood glaring fiercely at the limp frame of the old Chinaman, and as he glared his expression changed. Lying on the dirty floor not a yard from Sam Tûk’s feet was a ball of leaf opium! “Ha!” exclaimed Kerry, and he stooped to pick it up. As he did so, with a lightning movement of which the most astute observer could never have supposed him capable, Sam Tûk whipped a loaded rubber tube from his sleeve and struck Kerry a shrewd blow across the back of the skull. The Chief Inspector, without word or cry, collapsed upon his knees, and then fell gently forward—forward—and toppled face downwards before his assailant. His bowler fell off and rolled across the dirty floor.