The cellar explained also how she had turned her flashlight off and slipped through the hall and out while we searched the rooms.  She hadn’t gone back.  I couldn’t find her.  So I went on into Smithtown and sent a costly cable to my father.  His answer came to-night just before Silas Blackburn walked in.  He had talked with several of the survivors of those evil days.  He gave me a confirmation of everything I had gathered from the papers.  The Blackburns had quarrelled over a contract.  Robert had been struck over the head.  He wandered about the isthmus, half-witted, forgetting his name, nursing one idea.  Someone had robbed him, and he wanted his money back or a different kind of payment, but he couldn’t remember who, and he took it out in angry talk.  Then he disappeared, and people said he had gone to Spain.  Of course his wife suspected a good deal.  In Blackburn’s desk are pitiful and threatening letters from her which he ignored.  Then she died, and Blackburn thought he was safe.  But he took no chances.  Some survivor of those days might turn up and try blackmail.  It was safer to bury himself here.”

“Then,” Bobby said, “Maria must have brought her father with her when she came from Spain last summer.”

“Brought him or sent for him,” Paredes answered.  “She’s made most of her money on this side, you know.  And she’s as loyal and generous as she is impulsive.  Undoubtedly she had the doctors do what they could for her father, and when she got track of Silas Blackburn through you, Bobby, she nursed in the warped brain that dominant idea with her own Latin desire for justice and payment.”

“Then,” Graham said, “that’s what Silas Blackburn was afraid of instead of Bobby, as he tried to convince us to-night to cover himself.”

“One minute, Mr. Paredes,” Robinson broke in.  “Why did you maintain this extraordinary secrecy?  Nobody would have hurt you if you had put us on the right track and asked for a little help.  Why did you throw sand in our eyes?  Why did you talk all the time about ghosts?”

“I had to go on tiptoe,” Paredes smiled.  “I suspected there was at least one spy in the house.  So I gave the doctor’s ghost talk all the impetus I could.  I was like Howells, as I’ve told you, in believing the case couldn’t be complete without the discovery of the secret entrance of the room of death.  My belief in the existence of such a thing made me lean from the first to Silas Blackburn rather than Robert.  It’s a tradition in many families to hand such things down to the head of each generation.  Silas Blackburn was the one most likely to know.  Such a secret door had never been mentioned to you, had it, Bobby?”

Bobby shook his head.  Paredes turned and smiled at the haggard butler.

“I’m right so far, am I not, Jenkins?”

Jenkins bobbed his head jerkily.

“Then,” Paredes went on, “you might answer one or two questions.  When did the first letter that frightened your master come?”