But for the Greenwich bank the boat was headed; and pulling mightily against the current, the man struck out into mid-stream. They watched him for some time, silently, noting how he fought against the tide, sturdily heading for the point at which the signal had shown. Then: “What do you suggest?” asked Seton. “He may follow the Surrey bank up-stream.” “I suggest,” said Kerry, “that we drift. Once in Limehouse Reach we’ll hear him. There are no pleasure parties punting about that stretch.” “Let us pull out, then. I propose that we wait for him at some convenient point between the West India Dock and Limehouse Basin.” “Good,” rapped Kerry, thrusting the boat out into the fierce current. “You may have spent a long time in the East, sir, but you’re fairly wise on the geography of the lower Thames.” Gripped in the strongly running tide they were borne smoothly up-stream, using the oars merely for the purpose of steering. The gloomy mystery of the London river claimed them and imposed silence upon them, until familiar landmarks told of the northern bend of the Thames, and the light above the Lavender Pond shone out upon the unctuously moving water. Each pulling a scull they headed in for the left bank. “There’s a wharf ahead,” said Seton, looking back over his shoulder. “If we put in beside it we can wait there unobserved.” “Good enough,” said Kerry. They bent to the oars, stealing stroke by stroke out of the grip of the tide, and presently came to a tiny pool above the wharf structure, where it was possible to lie undisturbed by the eager current. Those limitations which are common to all humanity and that guile which is peculiar to the Chinese veiled the fact from their ken that the deserted wharf, in whose shelter they lay, was at once the roof and the gateway of Sin Sin Wa’s receiving office! As the boat drew in to the bank, a Chinese boy who was standing on the wharf retired into the shadows. From a spot visible down-stream but invisible to the men in the boat, he signalled constantly with a hurricane lantern. Three men from New Scotland Yard were watching the house of Sin Sin Wa, and Sin Sin Wa had given no sign of animation since, some hours earlier, he had extinguished his bedroom light. Yet George, drifting noiselessly up-stream, received a signal to the effect “police” while Seton Pasha and Chief Inspector Kerry lay below the biggest dope cache in London. Seton sometimes swore under his breath. Kerry chewed incessantly. But George never came. At that eerie hour of the night when all things living, from the lowest to the highest, nor excepting Mother Earth herself, grow chilled, when all Nature’s perishable handiwork feels the touch of death—a wild, sudden cry rang out, a wailing, sorrowful cry, that seemed to come from nowhere, from everywhere, from the bank, from the stream; that rose and fell and died sobbing into the hushed whisper of the tide. Seton’s hand fastened like a vise on to Kerry’s shoulder, and: