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 storie