“Very well!” commented Mr. Grimm, and finally:  “I think, perhaps, I owe you an apology, Miss Thorne—­another one.  The circumstances now, as they were at our previous meetings, are so unusual that—­is it necessary to go on?” There was a certain growing deference in his tone.  “I wonder if you account for Monsieur Boissegur’s disappearance as I do?” he inquired.

“I dare say,” and Miss Thorne leaned toward him with sudden eagerness in her manner and voice.  “Your theory is—?” she questioned.

“If we believe the servants we know that Monsieur Boissegur did not go out either by the front door or rear,” Mr. Grimm explained.  “That being true the French window by which you entered seems to have been the way.”

“Yes, yes,” Miss Thorne interpolated.  “And the circumstances attending the disappearance?  How do you account for the fact that he went, evidently of his own will?”

“Precisely as you must account for it if you have studied the situation here as I have,” responded Mr. Grimm.  “For instance, sitting at his desk there”—­and he turned to indicate it—­“he could readily see out the windows overlooking the street.  There is only a narrow strip of lawn between the house and the sidewalk.  Now, if some one on the sidewalk, or—­or—­”

“In a carriage?” promptly suggested Miss Thorne.

“Or in a carriage,” Mr. Grimm supplemented, “had attracted his attention—­some one he knew—­it is not at all unlikely that he rose, for no apparent reason, as he did do, passed along the hall—­”

“And through the French window, across the lawn to the carriage, and not a person in the house would have seen him go out?  Precisely!  There seems no doubt that was the way,” she mused.  “And, of course, he must have entered the carriage of his own free will?”

“In other words, on some pretext or other, he was lured in, then made prisoner, and—!”

He paused suddenly and his hand met Miss Thorne’s warningly.  The silence of the night was broken by the violent clatter of footsteps, apparently approaching the embassy.  The noise was unmistakable—­some one was running.

“The window!” Miss Thorne whispered.

She rose quickly and started to cross the room, to look out; Mr. Grimm sat motionless, listening.  An instant later and there came a tremendous crash of glass—­the French window in the hallway by the sound—­then rapid footsteps, still running, along the hall.  Mr. Grimm moved toward the door unruffled, perfectly self-possessed; there was only a narrowing of his eyes at the abruptness and clatter of it all.  And then the electric lights in the hall flashed up.

Before Mr. Grimm stood a man, framed by the doorway, staring unseeingly into the darkened room.  His face was haggard and white as death; his mouth agape as if from exertion, and the lips bloodless; his eyes were widely distended as if from fright—­clothing disarranged, collar unfastened and dangling.