“Yes, I know,” he agreed gently, turning to face her. “But I have walked the track myself, Miss Harcus, and I know about railways. There is nothing in land acquisition, even bad land, that endangers the lives of people on the train.”

“Isn’t there?” She allowed him to move on slowly and blend in with the others strolling between the flower beds. “Are you certain?”

“If land costs more than it should have done, or less,” he explained, “and the company owners put the difference in their own pockets instead of those of the shareholders, that is theft, but it does not affect the safety of the railway itself.”

She looked up at him earnestly. He could see the hurt and confusion in her face, the desperation mounting inside her. Why? What did she know about Dalgarno that she was still not telling him?

“What amounts of money could be involved?” she interrupted his thoughts. “A great deal, surely? Enough to keep an ordinary man in comfort for the rest of his life?”

Monk had a sudden start of memory of Arrol Dundas, so vivid he could see the lines in Dundas’s skin, the curve of his nose, and a gentleness in his eyes as he looked across at Monk. He was back at the trial again, seeing people’s faces drop in amazement as amounts of money were mentioned, sums that seemed unimaginable wealth to them but in railway terms were everyday. He could see the open mouths, hear the gasps of indrawn breath and the rustle of movement around the room, the scrape of fabric, the creak of whalebone stays.

What had happened to that money? Did Dundas’s widow have it? No, that was impossible. People did not keep the profit of crime. Had it disappeared? There must have been proof that he had had it at some time in order to convict him.

Monk refused even to consider the other possibility, that somehow he himself had had it. He knew enough of his own life in the police force to know such wealth would have been exposed.

Katrina was waiting for him to respond.

He jerked himself back to the present. “Yes, it would be a great deal of money,” he conceded.