“Why,” Bobby asked, “should that involve Katherine?”

“Howells may have written something damaging to her.  He knew she was devoted to your interests.”

Robinson called to them from the library.

“Won’t you please come in, Mr. Blackburn?”

Bobby and Graham continued to the library.  They found Rawlins gazing through the door of the private staircase.

“We could go up this way,” he was saying, “and across the old room so that she needn’t suspect.”

“What is he talking about?” Bobby asked Robinson angrily.

“You wanted to help,” Robinson answered, “so Rawlins and I are going to give you a chance.  We are about to search your cousin’s room.  We hope to find there an explanation of a part of the mystery—­the motive, at least, for Howells’s death; perhaps your own exoneration.  You’d do anything to have that, wouldn’t you?  You’ve said so.”

“At her expense!” Bobby cried.  “You’ve no right to go to her room.  She’s incapable of a share in such crimes.  Do you seriously think she could plan an escape from the grave and bring back to life a man three days dead?”

“Give me a human being that caused death,” Robinson answered, “and I’ll tackle the ghosts later.  You’re wrong if you think I’m going to quit cold because your grandfather looks like a dead thing that moves about and talks.  I shan’t give up to that madness until I’ve done everything in my power.  I would be a criminal myself if I failed to do as Rawlins wishes.  If your cousin’s skirts are clear no harm will be done.  I’m acting on the assumption that your confession was honest.  I want you to get Miss Perrine out of her room.  I want you to see that she stays downstairs while we search.”

“You’ve already searched her room.”

“Not since Rawlins—­”

Robinson caught himself.

“Never mind that.  It is necessary it should be searched to-night.  Even you’ll acknowledge it’s significant that all day when she has been downstairs her door has been locked.”

“It’s only significant,” Bobby flashed, “in view of your treatment of her yesterday.”

Robinson grinned.

“That will hardly go down.  Rawlins has hesitated to break in.  I’ve instructed him to do it now, if necessary.  For the last time, will you bring your cousin down?  Will you go through and unlock the door leading from the old bedroom to the private hall so we can get up?”

“No,” Bobby cried, “I wouldn’t do it if I believed you were right.  And I know you’re wrong.”

“Prove that we’re wrong.  Clear your cousin by helping us,” Robinson urged.

“Since you’re so determined,” Graham said quietly, “I’ll do it.”

“Hartley!  What are you thinking of?”

“Of showing them how wrong they are,” Graham said.  “I’ll tell her Doctor Groom wishes to speak to her about Mr. Blackburn.  I’ll warn him to keep her downstairs for a quarter of an hour.  That should give you plenty of time.”