Kerry started and clutched the arms of the chair.

“A dog!” he said.  “A dog!”

“The howling o’ a sma’ dog,” declared his wife; “and I thought ’twas a portent, an’ the great fear came o’er me again.  But as I prayed ’twas unfolder to me that the portent was no’ for yersel’ but for her—­the puir weak hairt ye ha’ tee save.”

She ceased speaking and the strange fey light left her eyes.  She dropped upon her knees beside Kerry, bending her head and throwing her arms about him.  He glanced down at her tenderly and laid his hands upon her shoulders; but he was preoccupied, and the next moment, his jaws moving mechanically, he was staring straight before him.

“A dog,” he muttered, “a dog!”

Mary Kerry did not move; until, a light of understanding coming into Kerry’s fierce eyes, he slowly raised her and stood upright himself.

“I have it!” he said.  “Mary, the case is won!  Twenty men have spent the night and early morning beating the river bank so that the very rats have been driven from their holes.  Twenty men have failed where a dog would have succeeded.  Mary, I must be off.”

“Ye’re no goin’ out again, Dan.  Ye’re weary tee death.”

“I must, my dear, and it’s you who send me.”

“But, Dan, where are ye goin’?”

Kerry grabbed his hat and cane from the sideboard upon which they lay, and: 

“I’m going for the dog!” he rapped.

Weary as he was and travel-stained, for once neglectful of that neatness upon which he prided himself, he set out, hope reborn in his heart.  His assertion that the very rats had been driven from their holes was scarce an exaggeration.  A search-party of twenty men, hastily mustered and conducted by Kerry and Seton Pasha, had explored every house, every shop, every wharf, and, as Kerry believed, every cellar adjoining the bank, between Limehouse Basin and the dock gates.  Where access had been denied them or where no one had resided they had never hesitated to force an entrance.  But no trace had they found of those whom they sought.

For the first time within Kerry’s memory, or, indeed, within the memory of any member of the Criminal Investigation Department, Detective-Sergeant Coombes had ceased to smile when the appalling truth was revealed to him that Sin Sin Wa had vanished—­that Sin Sin Wa had mysteriously joined that invisible company which included Kazmah, Mrs. Sin and Mrs. Monte Irvin.  Not a word of reprimand did the Chief Inspector utter, but his eyes seemed to emit sparks.  Hands plunged deeply in his pockets he had turned away, and not even Seton Pasha had dared to speak to him for fully five minutes.

Kerry began to regard the one-eyed Chinaman with a superstitious fear which he strove in vain to stifle.  That any man could have succeeded in converting a chandu-khan such as that described by Mollie Gretna into a filthy deserted dwelling such as that visited by Kerry, within the space of some thirty-six hours, was well nigh incredible.  But the Chief Inspector had deduced (correctly) that the exotic appointments depicted by Mollie were all of a detachable nature—­merely masking the filthiness beneath; so that at the shortest notice the House of a Hundred Raptures could be dismantled.  The communicating door was a larger proposition, but that it was one within the compass of Sin Sin Wa its effectual disappearance sufficiently demonstrated.