“Exactly—but I thought you might be interested enough to enquire the result of my efforts. Or doesn’t thought interest you?”

“Very much indeed,” Frant hastened to reassure him.

“I am delighted to hear it. Well, then, after some hard and decidedly tiring thinking”—Mallett stifled an enormous yawn—“I have come to some definite conclusions. One definite conclusion, perhaps it would be more accurate to say, from which the rest follows as a matter of course.”

“And that conclusion is——?”

“The identity of Colin James.”

Frant took a sharp breath of excitement. The inspector went on calmly: “That identity once established, it becomes perfectly simple to ascertain who killed Ballantine, and why, and how and all the rest of the story.”

“Of course, we’ve always assumed that. But who is James?”

“Unfortunately,” Mallett proceeded, “having done that, we are only halfway to our objective. The business of detection”, he continued pedantically, “is in two parts. First, we have to discover the criminal. That can be done, as I have done it in this case, by pure deduction from sometimes very slender evidence. Second, we have to prove his guilt to the satisfaction of a jury. That, as you know very well, is often the hardest part of our task. I think that in this instance it won’t turn out too impossibly difficult, now that I know exactly what I am looking for. And for a start——”

Frant could bear it no longer. “But James! James” he almost shouted. “Who is Colin James?”

“As I was saying—for a start, I think I shall go and have another chat with Gaveston.”

Frant stopped in the act of repeating his question, open-mouthed, while he groped for the significance of the name. “Gaveston?” he said at last. “The silly old man who signed the letter? I don’t understand. What earthly good can he be?”

“No, not that one, but his brother, Lord Bernard. A much more interesting person to talk to, altogether. I shall enjoy seeing him again. Last time we met, he dropped something in the course of conversation that makes me think he has some knowledge which will be useful.”

The sergeant shrugged his shoulders. “This is all very mysterious,” he grumbled. “I’m supposed to be helping you in this case, and you won’t tell me the most important thing in it. If you won’t, you won’t, I suppose, but I don’t see why I should be kept in the dark.”

Mallett’s eyes were dancing mischievously. “Think, Frant, think,” he taunted him. “It’s not so difficult when you get down to it. We had a list, didn’t we? Let’s see, now, who were they?”

“Eales, Du Pine, Fanshawe, Harper, Crabtree,” said Frant rapidly, “and——”

“Yes?”

“And, of course—X.”

“I think we can leave him out now.”

His pencil played busily across a writing-pad. Then he tore off the sheet and passed it across the desk.