"Because Papa was concerned there was going to be an accident, and he would not come into the offices to discuss it anymore," she said immediately. "He was going to speak to the authorities. They would have had to close down the works until they had investigated, and of course discovered that it was completely untrue. But they could not afford to take my husband's word for it, when men's lives are at risk. My father was mad, Mr. Monk! He had lost all sense of proportion."

"So you arranged this meeting?"

"Yes."

"But your husband didn't go!" Monk pointed out. "He was at a party until long after midnight. You told the police that you attended it with him. Was that not true?"

"Yes, it was true. I... I thought my father must have refused to meet Alan. He was ... stubborn." Her gaze did not waver from his.

"Is that what Mr. Argyll said?" he asked.

She hesitated, but only for a moment. "Yes."

"I see." He did see. He had never supposed that Alan Argyll intended to shoot Havilland himself. He had paid the assassin with the black hair and the narrow-bridged nose to do that. "Thank you, Mrs. Argyll."

"Do you suppose he paid the money himself, or had someone else whom he trusted do it?" Monk asked when they were outside, matching his step to Runcorn's on the icy pavement.

"Toby?"

"Probably, but not necessarily. Who would even know where to find an assassin for money?"

Runcorn thought for a while, walking in silence. "Whom else would he trust?" he said at last.

"Can you trace the funds?" Monk asked him.

"Unless he's been saving it up penny by penny over the years, certainly I can. Havilland found something and Alan Argyll couldn't wait. He had to have got the money out of the bank, or wherever he kept it, and paid the assassin within a day or two of the actual murder. It's my case, Monk. I've got the men to put on it, and the authority to look at bank accounts or whatever it takes. I'll find out where Argyll was every minute of the week before Havilland was shot. And after. Unless he's a fool, he won't have paid all of it until the deed was done."

"What do you want me to do?" The words were not easy for Monk to say, but Runcorn's plan made sense. He could deploy his men to search, to question, to force out answers that Monk could not. And Monk needed to return to Wapping and start earning some of the loyalty he was going to need from his own men. Havilland's death was nothing to do with them.

Runcorn smiled. "Go back to your river," he replied. "I'll send you a message."

After two days the letter came, written in Runcorn's careful, overly neat hand. It was brought by a messenger and given to Monk personally.

Dear Monk,