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: 

“Merciful God!” he whispered; “what was it?  Who was it?”

“If it wasn’t a spirit it was a woman,” replied Kerry hoarsely; “and a woman very near to her end.”

“Kerry!”—­Seton Pasha had dropped all formality—­“Kerry—­if it calls for all the men that Scotland Yard can muster, we must search every building, down to the smallest rathole in the floor, on this bank—­and do it by dawn!”

“We’ll do it,” rapped Kerry.

PART FOURTH

THE EYE OF SIN SIN WA

CHAPTER XXXII

CHINESE MAGIC

Detective-Sergeant Coombes and three assistants watched the house of Sin Sin Wa, and any one of the three would have been prepared to swear “on the Book” that Sin Sin Wa was sleeping.  But he who watches a Chinaman watches an illusionist.  He must approach his task in the spirit of a psychical inquirer who seeks to trap a bogus medium.  The great Robert Houdin, one of the master wizards of modern times, quitted Petrograd by two gates at the same hour according to credible witnesses; but his performance sinks into insignificance beside that of a Chinese predecessor who flourished under one of the Ming emperors.  The palace of this potentate was approached by gates, each having twelve locks, and each being watched by twelve guards.  Nevertheless a distinguished member of the wizard family not only gained access to the imperial presence but also departed again unseen by any of the guards, and leaving all the gates locked behind him!  If Detective-Sergeant Coombes had known this story he might not have experienced such complete confidence.