At that the dealer bowed, took up his hat from the table, and prepared to depart.  Lewison opened the door and stood aside.

“Good morning, gentlemen,” said Meyerstein.

As Lewison was about to follow him—­

“Since you do not intend to open the box,” he said, turning, his hand upon the door knob, “have you any idea of its contents?”

“None,” replied Smith; “but with my present inadequate knowledge of its history, I do not care to open it.”

Lewison smiled skeptically.

“Probably you know best,” he said, bowed to us both, and retired.

When the door was closed—­

“You see, Petrie,” said Smith, beginning to stuff tobacco into his briar, “if we are ever short of funds, here’s something”—­pointing to the Tulun-Nur box upon the table—­“which would retrieve our fallen fortunes.”

He uttered one of his rare, boyish laughs, and began to pace the carpet again, his gaze always set upon our strange treasure.  What did it contain?

The manner in which it had come into our possession suggested that it might contain something of the utmost value to the Yellow group.  For we knew the house of John Ki to be, if not the head-quarters, certainly a meeting-place of the mysterious organization the Si-Fan; we knew that Dr. Fu-Manchu used the place—­Dr. Fu-Manchu, the uncanny being whose existence seemingly proved him immune from natural laws, a deathless incarnation of evil.

My gaze set upon the box, I wondered anew what strange, dark secrets it held; I wondered how many murders and crimes greater than murder blackened its history.

“Smith,” I said suddenly, “now that the mystery of the absence of a key-hole is explained, I am sorely tempted to essay the task of opening the coffer.  I think it might help us to a solution of the whole mystery.”

“And I think otherwise!” interrupted my friend grimly.  “In a word, Petrie, I look upon this box as a sort of hostage by means of which—­ who knows—­we might one day buy our lives from the enemy.  I have a sort of fancy, call it superstition if you will, that nothing—­not even our miraculous good luck—­could save us if once we ravished its secret.”

I stared at him amazedly; this was a new phase in his character.

“I am conscious of something almost like a spiritual unrest,” he continued.  “Formerly you were endowed with a capacity for divining the presence of Fu-Manchu or his agents.  Some such second-sight would appear to have visited me now, and it directs me forcibly to avoid opening the box.”

His steps as he paced the floor grew more and more rapid.  He relighted his pipe, which had gone out as usual, and tossed the match-end into the hearth.

“To-morrow,” he said, “I shall lodge the coffer in a place of greater security.  Come along, Petrie, Weymouth is expecting us at Scotland Yard.”

CHAPTER XI