“What! for God’s sake!” cried Harren hoarsely.

“I don’t know yet.  Wait; let me study it.”

“Can you not see her face, her eyes? Don’t you see that exquisite slim figure standing there by the curtain?” demanded Harren, laying his shaking finger on the photograph.  “Why, man, it is as clear, as clean cut, as distinct as though the picture had been taken in sunlight!  Do you mean to say that there is nothing there—­that I am crazy?”

“No.  Wait.”

“Wait!  How can I wait when you sit staring at her picture and telling me that you can’t see it, but that it is doubtless there?  Are you deceiving me, Mr. Keen?  Are you trying to humor me, trying to be kind to me, knowing all the while that I’m crazy—­”

“Wait, man!  You are no more crazy than I am.  I tell you that I can see something on the window pane—­”

He suddenly sprang up and walked to the window, leaning close and examining the glass.  Harren followed and laid his hand lightly over the pane.

“Do you see any marks on the glass?” demanded Keen.

Harren shook his head.

“Have you a magnifying glass?” asked the Tracer.

Harren pointed back to the table, and they returned to the photograph, the Tracer bending over it and examining it through the glass.

“All I see,” he said, still studying the photograph, “is a corner of a curtain and a window on which certain figures seem to have been cut. . . .  Look, Captain Harren, can you see them?”

“I see some marks—­some squares.”

“You can’t see anything written on that pane—­as though cut by a diamond?”

“Nothing distinct.”

“But you see her?”

“Perfectly.”

“In minute detail?”

“Yes.”

The Tracer thought a moment:  “Does she wear a ring?”

“Yes; can’t you see?”

“Draw it for me.”

They seated themselves side by side, and Harren drew a rough sketch of the ring which he insisted was so plainly visible on her hand: 

[Illustration:  Ring with an X]

“Oh,” observed the Tracer, “she wears the Seal of Solomon on her ring.”

Harren looked up at him.  “That symbol has haunted me persistently for three years,” he said.  “I have found it everywhere—­on articles that I buy, on house furniture, on the belts of dead ladrones, on the hilts of creeses, on the funnels of steamers, on the headstalls of horses.  If they put a laundry mark on my linen it’s certain to be this!  If I buy a box of matches the sign is on it.  Why, I’ve even seen it on the brilliant wings of tropical insects.  It’s got on my nerves.  I dream about it.”

[Illustration:  Cryptographic symbol]

“And you buy books about it and try to work out its mystical meaning?” suggested the Tracer, smiling.

But Harren’s gray eyes were serious.  He said:  “She never comes to me without that symbol somewhere about her. . . .  I told you she never spoke to me.  That is true; yet once, in a vivid dream of her, she did speak.  I—­I was almost ashamed to tell you of that.”