Doctor Groom was the first to relax.  He raised his great, hairy hand to the bed-post and grasped it.  His rumbling voice lacked its usual authority.  It vibrated with a childish wonder: 

“I’m reminded that it isn’t the first time there’s been blood from a man’s head on that pillow.”

Katherine nodded.

“What do you mean?” the detective snarled.  “There’s only one answer to this.  There must have been a mechanical post-mortem reaction.”

For a moment Doctor Groom’s laugh filled the old room.  It ceased abruptly.  He shook his head.

“Don’t be a fool, Mr. Policeman.  At the most conservative estimate this man has been dead more than thirteen hours.  Even a few instants after death the human body is incapable of any such reaction.”

“What then?” the detective asked.  “Some one of us, or one of the servants, must have overcome the locks again and deliberately disturbed the body.  That must be so, but I don’t get the motive.”

“It isn’t so,” Doctor Groom answered bluntly.

Already the detective had to a large extent controlled his bewilderment.

“I’d like your theory then,” he said dryly.  “You and Mr. Paredes have both been gossiping about the supernatural.  When you first came you hinted dark things.  You said he’d probably died what the world would call a natural death.”

“I meant,” the doctor answered, “only that Mr. Blackburn’s heart might have failed under the impulse of a sudden fright in this room.  I also said, you remember, that the room was nasty and unhealthy.  Plenty of people have remarked it before me.”

Graham touched the detective’s arm.

“A little while ago you admitted yourself that the room was uncomfortable.”

Doctor Groom smiled.  The detective faced him with a fierce belligerency.

“You’ll agree he was murdered.”

“Certainly, if you wish to call it that.  But I ask for the sharp instrument that caused death.  I want to know how, while Blackburn lay on his back, it was inserted through the bed, the springs, the mattress, and the pillow.”

“What are you driving at?”

Doctor Groom pointed to the dead man.

“I merely repeat that it isn’t the first time that pillow’s been stained from unusual wounds in the head.  Being, as you call it, a trifle superstitious, I merely ask if the coincidence is significant.”

Katherine cried out.  Bobby, in spite of his knowledge that sooner or later he would be arrested for his grandfather’s murder, stepped forward, nodding.

“I know what you mean, doctor.”

“Anybody,” the doctor said, “who’s ever heard of this house knows what I mean.  We needn’t talk of that.”

The detective, however, was insistent.  Paredes in his unemotional way expressed an equal curiosity.  Bobby and Katherine had been frightened as children by the stories clustering about the old wing.  They nodded from time to time while the doctor held them in the desolate room with the dead man, speaking of the other deaths it had sheltered.