"In the car, Bill. And how near can the car get to Jallands?"

"About six hundred yards."

"Yes. And on his way to Middleston, on some business or other, Mark stops the car, walks six hundred yards down the hill to Jallands, says, 'Oh, by the way, Mrs. Norbury, I don't think I ever told you that I have a shady brother called Robert,' walks six hundred yards up the hill again, gets into the car, and goes off to Middleston. Is that likely?"

Bill frowned heavily.

"Yes, but I don't see what you're getting at. Likely or not likely, we know he did do it."

"Of course he did. All I mean is that he must have had some strong reason for telling Mrs. Norbury at once. And the reason I suggest is that he knew on that morning-Monday morning, not Tuesday-that Robert was coming to see him, and had to be in first with the news.

"But-but-"

"And that would explain the other point-his instantaneous decision at breakfast to tell you all about his brother. It wasn't instantaneous. He knew on Monday that Robert was coming, and decided then that you would all have to know."

"Then how do you explain the letter?"

"Well, let's have a look at it."

Antony took the letter from his pocket and spread it out on the gra.s.s between them.

"Mark, your loving brother is coming to see you to-morrow, all the way from Australia. I give you warning, so that you will be able to conceal your surprise but not I hope your pleasure. Expect him at three or thereabouts."

"No date mentioned, you see," said Antony. "Just to-morrow."

"But he got this on Tuesday."

"Did he?"

"Well, he read it out to us on Tuesday."

"Oh, yes! he read it out to you."

Bill read the letter again, and then turned it over and looked at the back of it. The back of it had nothing to say to him.

"What about the postmark?" he asked.

"We haven't got the envelope, unfortunately."

"And you think that he got this letter on Monday."

"I'm inclined to think so, Bill. Anyhow, I think-I feel almost certain-that he knew on Monday that his brother was coming."

"Is that going to help us much?"

"No. It makes it more difficult. There's something rather uncanny about it all. I don't understand it." He was silent for a little, and then added, "I wonder if the inquest is going to help us.

"What about last night? I'm longing to hear what you make of that. Have you been thinking it out at all?"

"Last night," said Antony thoughtfully to himself. "Yes, last night wants some explaining."

Bill waited hopefully for him to explain. What, for instance, had Antony been looking for in the cupboard?

"I think," began Antony slowly, "that after last night we must give up the idea that Mark has been killed; killed, I mean, by Cayley. I don't believe anybody would go to so much trouble to hide a suit of clothes when he had a body on his hands. The body would seem so much more important. I think we may take it now that the clothes are all that Cayley had to hide."

"But why not have kept them in the pa.s.sage?"

"He was frightened of the pa.s.sage. Miss Norris knew about it."

"Well, then, in his own bedroom, or even, in Mark's. For all you or I or anybody knew, Mark might have had two brown suits. He probably had, I should think."

"Probably. But I doubt if that would rea.s.sure Cayley. The brown suit hid a secret, and therefore the brown suit had to be hidden. We all know that in theory the safest hiding-place is the most obvious, but in practice very few people have the nerve to risk it."

Bill looked rather disappointed.

"Then we just come back to where we were," he complained. "Mark killed his brother, and Cayley helped him to escape through the pa.s.sage; either in order to compromise him, or because there was no other way out of it. And he helped him by telling a lie about his brown suit."

Antony smiled at him in genuine amus.e.m.e.nt.

"Bad luck, Bill," he said sympathetically. "There's only one murder, after all. I'm awfully sorry about it. It was my fault for-"

"Shut up, you a.s.s. You know I didn't mean that."

"Well, you seemed awfully disappointed."

Bill said nothing for a little, and then with a sudden laugh confessed.

"It was so exciting yesterday," he said apologetically, "and we seemed to be just getting there, and discovering the most wonderful things, and now-"

"And now?"

"Well, it's so much more ordinary."

Antony gave a shout of laughter.

"Ordinary!" he cried. "Ordinary! Well, I'm dashed! Ordinary! If only one thing would happen in an ordinary way, we might do something, but everything is ridiculous." Bill brightened up again.

"Ridiculous? How?"

"Every way. Take those ridiculous clothes we found last night. You can explain the brown suit, but why the under clothes. You can explain the underclothes in some absurd way, if you like-you can say that Mark always changed his underclothes whenever he interviewed anybody from Australia-but why, in that case, my dear Watson, why didn't he change his collar?"

"His collar?" said Bill in amazement.

"His collar, Watson."

"I don't understand."

"And it's all so ordinary," scoffed Antony.