door closer than you have done you will find that it has fewer
coats of paint than the one leading to the corridor, that its frame is of
newer wood. In other words, it was cut through after the wing was built.
This panel was the original door, designed, with the private stairway and
the hall, for the exclusive use of the master of the house. Try it."

Robinson braced himself and shoved against the panel. It moved in its
grooves with a vibrant stirring.

"Rusty," he said.

Katherine started.

"That's what I heard each time," she cried.

Above his heavy black beard the doctor's cheeks whitened. Robinson made a
gesture of revulsion.

"That gives the nasty game away."

"Naturally," Paredes said, "and you must admit the game is as beautifully
simple as the panel. The instrument of death wasn't inserted through the
bedding as you thought inevitable, Doctor. Suppose you were lying in that
bed, asleep, or half asleep, and you were aroused by such a sound as
that in the wall behind you? What would you do? What would any man do
first of all?"

Robinson nodded.

"I see what you mean. I'd get up on my elbow. I'd look around as quickly
as I could to see what it was. I'd expose myself to a clean thrust. I'd
drop back on the bed, more thoroughly out of it than though I'd been
struck through the heart."

"Exactly," Paredes said, with the familiar shrug of his shoulders.

"You're sensible to give up this way," Robinson said. "It's the best plan
for you. What about Mr. Blackburn?"

Graham interfered.

"After all," he said thoughtfully. "I'm a lawyer, and it isn't fair,
Robinson. It's only decent to tell him that anything he says may be used
against him."

"Keep your mouth shut," Robinson shouted.

But Paredes smiled at Graham.

"It's very good of you, but I agree with the district attorney. There's
no point in being a clam now."

"Can you account for Silas Blackburn's return?" the doctor asked eagerly.

"That's right, Doctor," Paredes said. "Stick to the ghosts. I fancy
there are plenty in this house. I'm afraid we must look on Silas
Blackburn as dead."

"You don't mean we've been talking to a dead man?" Katherine whispered.

"Before I answer," Paredes said, "I want to have one or two things
straight. These men, Bobby, I really believe, think me capable of the
crimes in this house. I want to know if you accept such a theory. Do you
think I had any idea of killing you?"

Bobby studied the reserved face which ev