As they watched, a rigid little figure of horror backed slowly down the alcove stairs and into the room—­Billy, the Japanese, his Oriental placidity disturbed at last, incomprehensible terror written in every line of his face.

“Billy!”

“Billy—­what is it?”

The diminutive butler made a pitiful attempt at his usual grin.

“It—­nothing,” he gasped.  The Unknown relapsed in his chair—­ again the dazed stranger from nowhere.

Beresford took the Japanese by the shoulders.

“Now see here!” he said sharply.  “You’ve seen something!  What was it!”

Billy trembled like a leaf.

“Ghost!  Ghost!” he muttered frantically, his face working.

“He’s concealing something.  Look at him!” Miss Cornelia stared at her servant.

“No, no!” insisted Billy in an ague of fright.  “No, no!”

But Miss Cornelia was sure of it.

“Brooks, close that door!” she said, pointing at the terrace door in the alcove which still stood ajar after the entrance of the Unknown.

Bailey moved to obey.  But just as he reached the alcove the terrace door slammed shut in his face.  At the same moment every light in Cedarcrest blinked and went out again.

Bailey fumbled for the doorknob in the sudden darkness.

“The door’s locked!” he said incredulously.  “The key’s gone too.  Where’s your revolver, Beresford?”

“I dropped it in the alcove when I caught that man,” called Beresford, cursing himself for his carelessness.

The illuminated dial of Bailey’s wrist watch flickered in the darkness as he searched for the revolver—­as round, glowing spot of phosphorescence.

Lizzie screamed.  “The eye!  The gleaming eye I saw on the stairs!” she shrieked, pointing at it frenziedly.

“Quick—­there’s a candle on the table—­light it somebody.  Never mind the revolver, I have one!” called Miss Cornelia.

“Righto!” called Beresford cheerily in reply.  He found the candle, lit it—­

The party blinked at each other for a moment, still unable quite to co-ordinate their thoughts.

Bailey rattled the knob of the door into the hall.

“This door’s locked, too!” he said with increasing puzzlement.  A gasp went over the group.  They were locked in the room while some devilment was going on in the rest of the house.  That they knew.  But what it might be, what form it might take, they had not the remotest idea.  They were too distracted to notice the injured man, now alert in his chair, or the Doctor’s odd attitude of listening, above the rattle and banging of the storm.

But it was not until Miss Cornelia took the candle and proceeded toward the hall door to examine it that the full horror of the situation burst upon them.

Neatly fastened to the white panel of the door, chest high and hardly more than just dead, was the body of a bat.