No one took up the point thus raised.  Winter bent a searching, almost sorrowful glance at Furneaux, but the little man’s eyes were fixed on the ground, as though he were deep in thought.

In the charge room of the police station the twenty-five Chinamen awaited them.  Twenty-five pairs of oblique eyes gleamed at the four when they entered, but not a word was spoken.

Winter, of course, singled out Li Chang for a parley.

“Now,” he said, “tell me just what happened after you and these others went into the two houses in Charlotte Street.”

The Chinaman faced him imperturbably.  His manner was as unemotional and his words as slow and methodical as if he were selling jute in his East End warehouse.

“We asked to be admitted, and after giving the password and showing the sign there was no difficulty,” he said.  “We were in parties of three.  As you probably saw, I headed one, which entered No. 410.  My friend, Won Lung Foo, led the other.  The ivory skulls made matters simple.  We explained to the door-keepers that we had just arrived from China, and brought messages of great urgency.  Once inside, we gagged and bound the door-keepers.  Then we entered No. 412, where we knew that Wong Li Fu would be smoking opium with the remaining fourteen.”

“Were there seventeen in the gang, all told?” broke in Furneaux.

“Seventeen Manchus.  The rest are—­ paid men—­ of no account.”

“Queer,” muttered Furneaux, almost to himself.  “The story begins and ends with the number 17!”

Again did Winter strive to pierce his colleague with a look from those bulging eyes, but the little man was far too occupied with a singular numerical coincidence to pay any heed to him.

“Well, go on!” he said impatiently, glaring at the Chinaman.

“We went to the big room at the back,” continued Li Chang quietly, uttering each word separately, and evidently weighing it in his mind to test its accuracy before use, “and found Wong Li Fu.  Him we bound quickly, and very securely.  The others we tied in twos and threes.  Of course, we brought the two doorkeepers to the same room, so that you should experience no difficulty, but take them all together.”

Here Mr. Won Lung Foo broke in.  Evidently he could follow English better than speak it.

“Yes,” he said.  “We wantee you catchee Chineemans all togeller—­ muchee wantee!”

Then he smiled blandly, and his tongue rolled over his lips as though some fruit or sweetmeat had left a pleasant taste there.

“Then, if your surprise was so successful, what caused the fire?” said Winter, affecting a magnificent disregard of the plain facts.

Li Chang, for once, permitted his immobile features to show some semblance of anxious uncertainty.

“That,” he said, “is a mystery which can, perhaps, never be solved.  But it saves your Government much trouble.”

In those few words he expressed quite clearly the line he adhered to throughout a long cross-examination.  Neither Winter nor the commissioner could shake him.  The fire was an accident—­ the outcome of an extraordinary chance.  He knew nothing whatsoever of its origin.