“There is one about to visit you,” he said, “whom you know, whom I think you expect.  For it is written that she shall come and such events cast a shadow before them.  I, too, shall be present at your meeting!”

His eagle eyes opened widely; they burned with fanaticism.

“Already she is here!” he resumed suddenly, and bent as one listening.  “She comes under the archway; she crossed the courtyard —­and is upon the stair!  Admit her, effendim; I shall be close behind you!”

The door-bell rang.

With the consciousness that the black tube was directed toward the back of my head, I went and opened the door.  My mind was at work again, and busy with plans to terminate this impossible situation.

On the landing stood a girl wearing a simple white frock which fitted her graceful figure perfectly.  A white straw hat, of the New York tourist type, with a long veil draped from the back suited her delicate beauty very well.  The red mouth drooped a little at the corners, but the big violet eyes, like lamps of the soul, seemed afire with mystic light.

“Mr. Cavanagh,” she said, very calmly and deliberately, “there is only one way now to end all this trouble.  I come from the man who can return the slipper to where it belongs; but he wants his price!”

Her quiet speech served completely to restore my mental balance, and I noted with admiration that her words were so chosen as to commit her in no way.  She knew quite well that thus far she might appear in the matter with impunity, and she clearly was determined to say nothing that could imperil her.

“Will you please come in?” I said quietly—­and stood aside to admit her.

Exhibiting wonderful composure, she entered—­and there, in the badly lighted hallway came face to face with my other visitor!

It was a situation so dramatic as to seem unreal.

Away from that tall figure retreated the girl with the violet eyes —­and away—­until she stood with her back to the wall.  Even in the gloom I could see that her composure was deserting her; her beautiful face was pallid.

“Oh, God!” she whispered, all but inaudible—­“You!”

Hassan, grasping the black rod in his hand, signed to her to enter the study.  She stood quite near to me, with her eyes fixed upon him.  I bent closer to her.

“My revolver—­in left-hand table drawer,” I breathed in her ear.  “Get it.  He is watching me!”

I could not tell if my words had been understood, for, never taking her gaze from the Sheikh of the Assassins, she sidled into the study.  I followed her; and Hassan came last of all.  Just within the doorway he stood, confronting us.

“You have come,” he said, addressing the girl and speaking in perfect English but with a marked accent, “to open your impudent negotiations through Mr. Cavanagh for the return of the thrice holy relic to the Museum!  Your companion, the man, who is inspired by the Evil One, has even dared to demand ransom for the slipper from me!”