Wolfenden shook his head.

“Absolutely none,” he answered. “The only conversation we had, in which he showed any interest at all, was concerning my own people. By the bye, that reminds me! I told him of an incident which occurred at Deringham Hall last night, and he was certainly interested and curious. I chanced to look at him at an unexpected moment, and his appearance astonished me. I have never seen him look so keen about anything before.”

“Will you tell me the incident at once, please?” Harcutt begged eagerly. “It may contain the very clue for which I am hunting. Anything which interests Mr. Sabin interests me.”

“There is no secrecy about the matter,” Wolfenden said. “I will tell you all about it. You may perhaps have heard that my father has been in very poor health ever since the great Solent disaster. It unfortunately affected his brain to a certain extent, and he has been the victim of delusions ever since. The most serious of these is, that he has been commissioned by the Government to prepare, upon a gigantic scale, a plan and description of our coast defences and navy. He has a secretary and typist, and works ten hours a day; but from their report and my own observations I am afraid the only result is an absolutely unintelligible chaos. Still, of course, we have to take him seriously, and be thankful that it is no worse. Now the incident which I told Mr. Sabin was this. Last night a man called and introduced himself as Dr. Wilmot, the great mind specialist. He represented that he had been staying in the neighbourhood, and was on friendly terms with the local medico here, Dr. Whitlett. My father’s case had been mentioned between them, and he had become much interested in it. He had a theory of his own for the investigation of such cases which consisted, briefly of a careful scrutiny of any work done by the patient. He brought a letter from Dr. Whitlett and said that if we would procure him a sight of my father’s most recent manuscripts he would give us an opinion on the case. We never had the slightest suspicion as to the truth of his statements, and I took him with me to the Admiral’s study. However, while we were there, and he was rattling through the manuscripts, up comes Dr. Whitlett, the local man, in hot haste. The letter was a forgery, and the man an impostor. He escaped through the window, and got clean away. That is the story just as I told it to Mr. Sabin. What do you make of it?”

Harcutt stood up, and laid his hand upon the other’s shoulder.

“Well, I’ve got my clue, that’s all,” he declared; “the thing’s as plain as sunlight!”

Wolfenden rose also to his feet.

“I must be a fool,” he said, “for I certainly can’t see it.”

Harcutt lowered his tone.