"His sister," was the rather hazardous answer.

"Oh, his sister. Mr. Moore could not make out who the patient was. He thought it might be the husband who had returned. When I asked his name, to write a prescription for the chemist, Mrs. Grey said I might put it in hers--Grey."

"I thank you greatly for your courtesy, Dr. Cavendish."

"You are welcome," said the doctor. "Mind, I have not expressed any certain opinion as to his non-recovery. Don't go and alarm him. What I have said to you was said in confidence."

"You may depend upon me. Good night."

Mr. Detective Strange had to walk from Basham, for the last train was gone and his return half-ticket useless. Basham police station was nearly opposite the doctor's, and he stepped in there to leave a message on his way. In the satisfaction his visit had afforded him, he did not at all mind the night-walk: on the morrow, the long-sought-for Salter, who had dodged them so vexatiously, would be in their hands, the prey would have fallen. A satisfaction, however, that was not without alloy, in the damping circumstances that encompassed the man's state of health. And for that he could but feel compassion.

Midnight was chiming from the clock at Foxwood as he reached the Maze--for he preferred to take that roundabout way. Halting at the gate, he looked about and listened for a minute or two. Then he let himself in with his master-key, and went through the labyrinth.

The house lay in silence. All seemed still as the grave. There was no light, no sound, no token of illness inside; no, nor even of inmates. He gently put the said key in the entrance-door to see if it would yield. No: the door was not only locked but bolted and barred. He went to the summer-house, leading up from the underground places, and found the trapdoor there also bolted and barred within. All was as secure as wary hands could make it.

"And it is welcome to remain so until to-morrow," breathed the detective as he turned to thread his silent steps back through the maze; "but then, Mr. Philip Salter, you are mine. Neither bolts nor bars can save you then."

And he finally let himself out again at the gate with that ingenious instrument, the key. To be polite, we will apply a French name to it, and call it a passe-partout.