“Who are you?” he demanded; “and what business have you with the Si-Fan?”

The woman’s eyes opened more widely, and the smile disappeared from her face.

“The Si-Fan!” she repeated slowly.  “I don’t know what you mean, Inspector.”

“I am not an Inspector,” snapped Smith, “and you know it well enough.  You have one chance—­your last.  To whom were you to deliver the box? when and where?”

But the blue eyes remained upraised to the grim tanned face with a look of wonder in them, which, if assumed, marked the woman a consummate actress.

“Who are you?” she asked in a low voice, “and what are you talking about?”

Inactive, I stood by the door watching my friend, and his face was a fruitful study in perplexity.  He seemed upon the point of an angry outburst, then, staring intently into the questioning eyes upraised to his, he checked the words he would have uttered and began to click his teeth together again.

“You are some servant of Dr. Fu-Manchu!” he said.

The girl frowned with a bewilderment which I could have sworn was not assumed.  Then—­

“You said I had one chance a moment ago,” she replied.  “But if you referred to my answering any of your questions, it is no chance at all.  We have gone under, and I know it.  I am not complaining; it’s all in the game.  There’s a clear enough case against us, and I am sorry”—­suddenly, unexpectedly, her eyes became filled with tears, which coursed down her cheeks, leaving little wakes of blackness from the make-up upon her lashes.  Her lips trembled, and her voice shook.  “I am sorry I let him do it.  He’d never done anything—­not anything big like this—­before, and he never would have done if he had not met me....”

The look of perplexity upon Smith’s face was increasing with every word that the girl uttered.

“You don’t seem to know me,” she continued, her emotion growing momentarily greater, “and I don’t know you; but they will know me at Bow Street.  I urged him to do it, when he told me about the box to-day at lunch.  He said that if it contained half as much as the Kuren treasure-chest, we could sail for America and be on the straight all the rest of our lives....”

And now something which had hitherto been puzzling me became suddenly evident.  I had not removed the wig worn by the dead man, but I knew that he had fair hair, and when in his last moments he had opened his eyes, there had been in the contorted face something faintly familiar.

“Smith!” I cried excitedly, “it is Lewison, Meyerstein’s clerk!  Don’t you understand? don’t you understand?”

Smith brought his teeth together with a snap and stared me hard in the face.

“I do, Petrie.  I have been following a false scent.  I do!”

The girl in the chair was now sobbing convulsively.

“He was tempted by the possibility of the box containing treasure,” I ran on, “and his acquaintance with this—­lady—­who is evidently no stranger to felonious operations, led him to make the attempt with her assistance.  But”—­I found myself confronted by a new problem—­“what caused his death?”