Robinson joined in Rawlins’s laugh.

“Why go outside for that?”

Paredes started.

“You never mean—­”

“You bet we do,” Rawlins said.  “If what I’ve doped out hadn’t been so we’d have caught her long before.  We’re not blind, and we haven’t missed the nerve with which she helped the doctor fix you up.  We haven’t caught her before because her headquarters have been right in this house all the time.  You remember the other night, Mr. Robinson.  You’d just questioned her in the court and had threatened to question him, too, when she came in here ahead of us and slipped out the back way.  She must have told him to follow because they had to talk, undisturbed by us.  They went by different roads to the deserted house where a light had been seen before.  We happened to hit his trail first and followed it.  I’ll guarantee you didn’t see her when you first came in.”

Robinson shook his head.

“Mr. Graham kept me busy, and I rather waited for your report before pushing things.  I didn’t see her or question her until after Mr. Graham and Mr. Blackburn had started for New York.”

“And she could have sneaked in the back way any time before that,” Rawlins said.

“It’s utter nonsense!” Graham cried.

Rawlins turned on him.

“See here, Mr. Graham, you’ve been trying to fight me off this way all afternoon.  It won’t do.”

“Katy’s a good girl,” Silas Blackburn quavered.

With a growing discomfort Bobby realized that when the woman had cried near the graveyard he had reached out for Katherine and had failed to find her.  Moreover, the night Graham and he had heard the crying in the old room she had stood alone in the corridor.  It was easily conceivable that the turn of events after Robinson’s arrival should have made it necessary for conspirators to consult free from any danger of disturbance.  But Katherine, he told himself, was assuredly the victim of coincidence.  He couldn’t picture her entangled in any of Paredes’s purposes.  Her dislike of the man was complete and open.  But he saw that Rawlins out of the mass of apparently inexplicable clues had extracted this material one and would follow it desperately no matter who was hurt; and Robinson was behind him.  That accounted for their frequent excursions upstairs during the afternoon, for Rawlins’s ascent as soon as they had returned from the grave.  They had evidently found something to sharpen their suspicions, and Graham probably knew what it was.

Robinson took out his watch.

“We can’t put this off too late,” he mused.

The detective at his heels, he walked to the library.  Bobby started after them.  Graham caught him and they crossed the dining room together.

“What do they mean to do?” Bobby asked.

“I have been afraid of it since this afternoon,” Graham answered.  “I haven’t cared to talk about it.  I had hoped to hold them off.  They intend to search Katherine’s room.  I think they believe she has something important hidden there.  I’ve been wondering if they’ve got track of Howells’s report which we told Jenkins to hide.”