Miss Cornelia made a movement to question him further.  Beresford stopped her with his hand uplifted.

“Just a moment, Miss Van Gorder.  Anderson ought to know of this.”

He started for the door without perceiving the flash of keen intelligence and alertness that had lit the Unknown’s countenance for an instant, as once before, at the mention of the detective’s name.  But just as he reached the door the detective entered.

He halted for a moment, staring at the strange figure of the Unknown.

“A new element in our mystery, Mr. Anderson,” said Miss Cornelia, remembering that the detective might not have heard of the mysterious stranger before—­as he had been locked in the billiard room when the latter had made his queer entrance.

The detective and the Unknown gazed at each other for a moment—­the Unknown with his old expression of vacant stupidity.

“Quite dazed, poor fellow,” Miss Cornelia went on.  Beresford added other words of explanation.

“He doesn’t remember what happened to him.  Curious, isn’t it?”

The detective still seemed puzzled.

“How did he get into the house?”

“He came through the terrace door some time ago,” answered Miss Cornelia.  “Just before we were locked in.”

Her answer seemed to solve the problem to Anderson’s satisfaction.

“Doesn’t remember anything, eh?” he said dryly.  He crossed over to the mysterious stranger and put his hand under the Unknown’s chin, jerking his head up roughly.

“Look up here!” he commanded.

The Unknown stared at him for an instant with blank, vacuous eyes.  Then his head dropped back upon his breast again.

“Look up, you—­” muttered the detective, jerking his head again.  “This losing your memory stuff doesn’t go down with me!” His eyes bored into the Unknown’s.

“It doesn’t—­go down—­very well—­with me—­either,” said the Unknown weakly, making no movement of protest against Anderson’s rough handling.

“Did you ever see me before?” demanded the latter.  Beresford held the candle closer so that he might watch the Unknown’s face for any involuntary movement of betrayal.

But the Unknown made no such movement.  He gazed at Anderson, apparently with the greatest bewilderment, then his eyes cleared, he seemed to be about to remember who the detective was.

“You’re—­the—­Doctor—­I—­saw—­downstairs—­aren’t you?” he said innocently.  The detective set his jaw.  He started off on a new tack.

“Does this belong to you?” he said suddenly, plucking from his pocket the battered gold watch that Beresford had found and waving it before the Unknown’s blank face.

The Unknown stared at it a moment, as a child might stare at a new toy, with no gleam of recognition.  Then—­

“Maybe,” he admitted.  “I—­don’t—­know.”  His voice trailed off.  He fell back against Bailey’s arm.