Minute after minute passed, and still nothing.  There was not even the whisper of a wind-stirred drapery.  He was about to rise when, suddenly, with no other noise than that of the sharp click of the switch, the electric lights in the room blazed up brilliantly.  The glare dazzled Mr. Grimm with its blinding flood, but he didn’t move.  Then softly, almost in a whisper: 

“Good evening, Mr. Grimm.”

It was a woman’s voice, pleasant, unsurprised, perfectly modulated.  Mr. Grimm certainly did not expect it now, but he knew it instantly—­there was not another quite like it in the wide, wide world—­and though he was still blinking a little, he came to his feet courteously.

“Good morning, Miss Thorne,” he corrected gravely.

Now his vision was clearing, and he saw her, a graceful figure, silhouetted against the rich green of the wall draperies.  Her lips were curled the least bit, as if she might have been smiling, and her wonderful eyes reflected a glint of—­of—­was it amusement?  The folds of her evening dress fell away from her, and one bare, white arm was extended, as her hand still rested on the switch.

“And you didn’t hear me?” still in the half whisper.  “I didn’t think you would.  Now I’m going to put out the lights for an instant, while you pull the shades down, and then—­then we must have a—­a conference.”

The switch snapped.  The lights died as suddenly as they had been born, and Mr. Grimm, moving noiselessly, visited each of the four windows in turn.  Then the lights blazed brilliantly again.

“Just for a moment,” Miss Thorne explained to him quietly, and she handed him a sheet of paper.  “I want you to read this—­read it carefully—­then I shall turn out the lights again.  They are dangerous.  After that we may discuss the matter at our leisure.”

Mr. Grimm read the paper while Miss Thorne’s eyes questioned his impassive face.  At length he looked up indolently, listlessly, and the switch snapped.  She crossed the room and sat down; Mr. Grimm sat beside her.

“I think,” Miss Thorne suggested tentatively, “that that accounts perfectly for Monsieur Boissegur’s disappearance.”

“It gives one explanation, at least,” Mr. Grimm assented musingly.  “Kidnapped—­held prisoner—­fifty thousand dollars demanded for his safety and release.”  A pause.  “And to whom, may I ask, was this demand addressed?”

“To Madame Boissegur,” replied Miss Thorne.  “I have the envelope in which it came.  It was mailed at the general post-office at half-past one o’clock this afternoon, so the canceling stamp shows, and the envelope was addressed, as the letter was written, on a typewriter.”

“And how,” inquired Mr. Grimm, after a long pause, “how did it come into your possession?” He waited a little.  “Why didn’t Monsieur Rigolot report this development to me this afternoon when I was here?”

“Monsieur Rigolot did not inform you of it because he didn’t know of it himself,” she replied, answering the last question first.  “It came into my possession directly from the hands of Madame Boissegur—­she gave it to me.”