Ah Fung’s oblique eyes regarded him with an expression difficult to analyze, but partly it was murder. He made no attempt to obey the order. Meanwhile the dog, whining and scratching furiously, had exposed the greater part of a stone slab somewhat larger than those adjoining it, and having a large crack or fissure in one end. “For the last time,” said Kerry, drawing the man’s head back so that his breath began to whistle through his nostrils, “open that trap.” As he spoke he released Ah Fung, and Ah Fung made one wild leap towards the stairs. Kerry’s fist caught him behind the ear as he sprang, and he went down like a dead man upon a small heap of coal which filled the angle of the cellar. Breathing rapidly and having his teeth so tightly clenched that his maxillary muscles protruded lumpishly, Kerry stood looking at the fallen man. But Ah Fung did not move. The dog had ceased to scratch, and now stood uttering short staccato barks and looking up at the Chief Inspector. Otherwise there was no sound in the house, above or below. Kerry stooped, and with his handkerchief scrupulously dusted the stone slab. The spaniel, resentment forgotten, danced excitedly beside him and barked continuously. “There’s some sort of hook to fit in that crack,” muttered Kerry. He began to hunt about among the debris which littered one end of the cellar, testing fragment after fragment, but failing to find any piece of scrap to suit his purpose. By sheer perseverance rather than by any process of reasoning, he finally hit upon the piece of bent wire which was the key to this door of Sin Sin Wa’s drug warehouse. One short exclamation of triumph he muttered at the moment that his glance rested upon it, and five seconds later he had the trapdoor open and was peering down into the narrow pit in which wooden steps rested. The spaniel began to bark wildly, whereupon Kerry grasped him, tucked him under his arm, and ran up to the room above, where he deposited the furiously wriggling animal. He stepped quickly back again and closed the upper door. By this act he plunged the cellar into complete darkness, and accordingly he took out from the pocket of his rain-drenched overall the electric torch which he always carried. Directing its ray downwards into the cellar, he perceived Ah Fung move and toss his hand above his head. He also detected a faint rattling sound. “Ah!” said Kerry. He descended, and stooping over the unconscious man extracted from the pocket of his baggy blue trousers four keys upon a ring. At these Kerry stared eagerly. Two of them belonged to yale locks; the third was a simple English barrel-key, which probably fitted a padlock; but the fourth was large and complicated. “Looks like the key of a jail,” he said aloud.