He had, indeed, reached some conclusions already.  These might not be correct, yet they were already implanted in his mind.  The guests of the night were mere puppets, having no real connection with the game being played, utterly ignorant of what was going on behind the scenes.  The only one present having any real part was Percival Coolidge, and West had taken an instinctive dislike to this man.  Moreover, he had some reason to believe this feeling was warmly reciprocated; that the latter already suspected and watched him.  Only one explanation flashed into his mind to account for Miss Coolidge’s unexpected announcement of an engagement between them—­this would excuse any future intimacy; would enable them to meet alone freely without arousing comment.  She had deliberately chosen this course to disarm suspicion, and had failed to warn him in advance that she might test his nerve and discretion.  This appealed to him as the most reasonable explanation of the situation.  But beyond this vague guess, it was impossible to delve.  He possessed no facts, no knowledge; he could only keep faith in her, and wait the time of explanation.

Tired by the uselessness of such thinking West finally sought the bed, and must have slept, although scarcely aware that he had closed his eyes.

Some slight noise aroused him.  The door leading into the hall, which he had failed to lock, stood partially ajar, and his eyes caught the vague glimpse of a figure gliding swiftly through the opening.  With one bound he was upon his feet, springing recklessly forward.  The hall was dark, but for a patch of moonlight at the further end.  Against this he caught an instant, flitting glimpse of the intruder.  It was a woman, yet even as his eyes told him this, she seemed to vanish into thin air—­the hall was empty.

CHAPTER IV

MISS COOLIDGE EXPLAINS

Vague and indistinct as was that fleeting vision in the moonlight, West felt no doubt as to the identity of his visitor—­the woman was Natalie Coolidge.  His one glimpse of her vanishing figure assured him of this fact, and he drew back instantly, unwilling to follow.  Where she had gone he neither knew, nor cared.  She had come to his room secretly, supposing him asleep, and this surprising knowledge dominated his mind.  What could such an act mean?  This was certainly a home of respectability, of wealth.  The guests being entertained were evidence of that; yet this secret entrance into his private apartment at such an hour suggested theft, or even some more desperate crime.  There was mystery here, at least, a mystery beyond his power of discernment.  However, this recognition rather hardened him to his task, than otherwise.  He had been forced into the strange environment, and now meant to penetrate its every secret.