“A man,” he declared, “who for twenty years can deceive his master as utterly and completely as Craig has done me, who is capable of such diabolical outrages, and who, when capture stares him in the face, is capable of an escape such as he made to-day, is outside the laws of probability.  Personally, I do not believe that I shall ever again see the face of my servant, any more than that you, Quest, will entirely solve the mystery of these murders and the theft of the Rheinholdt jewels.”

Lenora, who, with her hat on, was packing a small bag at the other end of the room, glanced up for a moment.

[Illustration:  Quest is mystified at finding the jewels in the black box, which was on the floor.]

[Illustration:  “Sure an’ me name’s not Craig—­it’s Marty O’TOOLE, sir.”  They had fooled the criminologist.]

“The man is a demon!” she exclaimed.  “He would have sacrificed us all, if he could.  When I think of poor Laura lying there in the hospital, crushed almost to death, so that he could save his miserable carcass, and realise that he is free, I feel—­”

She stopped short.  Quest looked at her and nodded.

“Don’t mind hurting our feelings, Lenora,” he said.  “French and I are up against it all right.  We’re second best, at the present moment—­I’ll admit that—­but the end hasn’t come yet.”

“I am sorry,” she murmured.  “I was led away for a moment.  But, Mr. Quest,” she went on piteously, “can’t we do something?  Laura’s so brave.  She tried to laugh when I left her, an hour ago, but I could see all the time that she was suffering agony.  Fancy a man doing that to a woman!  It makes me feel that I can’t rest or sleep.  I think that when I have left the hospital I shall just walk up and down the streets and watch and search.”

Quest shook his head.

“That sort of thing won’t do any good,” he declared.  “It isn’t any use, Lenora, working without a plan.  That’s why I’m here now, waiting.  I want to formulate a plan first.”

“Who are we,” the Professor asked drearily, “to make plans against a fiend like that?  What can we do against men who have revolving staircases and trolley-loads of river pirates waiting for them?  You may be a scientific criminologist, Quest, but that fellow Craig is a scientific criminal, if ever there was one.”

Quest crossed the room towards his cigar cabinet, and opened it.  His little start was apparent to both of them.  Lenora laid down the bag which she had just lifted up.  The Professor leaned forward in his chair.

“What is it, Quest?” he demanded.

Quest stretched out his hand and picked up from the top of the cigars a small black box!  He laid it on the table.

“Unless I am very much mistaken,” he said, “it is another communication from our mysterious friend.”