"You don't have a choice now," Rathbone said quietly. "At least not as far as Sixsmith is concerned. I'll prosecute, by all means, and uncover everything I can. Meanwhile, you find out more about this mysterious assassin. Show who contacted him, if he ever took the second payment, if he knows who employed him. Above all, you need to show what Havilland was going to do that was sufficient to make Argyll want to kill him. So far all you have is an engineer who lost his nerve and became a nuisance. Sane men don't commit murder for that. Give me chapter and verse of what Argyll would lose, and connect it to him, not just to Sixsmith."

Monk stood up. "I'll find it! How long have I?"

"Till it comes to trial? Three weeks."

"Then I'd better start." He moved towards the door.

"Monk!"

He turned back. "Yes?"

"If you're right and it is Argyll, be careful. He's a very powerful man and you work in a dangerous job."

Monk stared at Rathbone with sudden surprise. There was a gentleness in his face he had not expected to see. "I will," he promised. "I have good men around me."

Monk began by going back to speak with Runcorn. The superintendent was probably as aware as Rathbone of the thinness of the case; nevertheless, Monk outlined it in legal terms while Runcorn sat behind his desk and listened grimly.

"Need to know more about this man in the mews," he said when Monk had finished. "Might get a better description of him if we ask the cabbie again. And we'll have to ask Mrs. Ewart to see if she can say anything more."

She was surprised to see them again, but it was apparent that she was not displeased. She was wearing a woollen dress of a dark, rich wine color, and she looked less tense than she had the previous time. Monk wondered if that was in any part related to the fact that her brother was not at home at this hour.

She received them in the withdrawing room, where there was a bright fire sending its heat into the air. The room was not what Monk would have expected. There was a pretentiousness about it that took away something of the comfort. The paintings on the walls were big and heavily framed, the kind of art one chooses to impress rather than because one likes it. There was an impersonal feel to them, as there was to the carved ivory ornaments on the mantelpiece and the few leather-bound books in a case against the wall. The volumes sat together uniform in size and color, immaculate, as though no one ever read them. Then he remembered that Mrs. Ewart was a widow and this was Barclay's house, not hers. He wondered for a moment what her own choice would have been.