“Yes. I was working on an investigation for her.” Now the die was cast, but he could not have hidden it, and neither should he want to. It was one coat button, easily enough explained. There might even be people in the gardens who had seen them and would recall the gesture in which she had accidentally ripped it off. “I can help,” he went on. Now that fierce anger overtook the initial shock, he wanted to. He wanted to be revenged for her, to find who had done this and see him punished. It was all he could do for her now. He had failed in everything else, but she had wanted revenge; he remembered very clearly the fury in her face. He could get at least that for her.

Runcorn’s eyes were wide. He let out his breath slowly. “So you weren’t here by accident. I should have known. What would you be doing in Cuthbert Street at this hour of the evening?” It was a rhetorical question to which he expected no answer. “What was it, this case you were working on?” he asked. “Do you know who did this to her?”

“No, I don’t know,” Monk replied. “But I’ve an idea, and I’ll damn well find out . . . and prove it! She was betrothed to a Michael Dalgarno, a senior employee of Baltimore and Sons, a railway company—”

“Just a minute!” Runcorn interrupted him. “Wasn’t there a Nolan Baltimore murdered in Leather Lane just a few weeks ago? Is that some connection with this?”

“None that I’ve been able to find,” Monk admitted. “Looks like Baltimore simply went to enjoy his pleasures and got involved in a fight that ended badly. Perhaps he didn’t pay enough, or more likely he was drunk and picked a quarrel.”

“So what were you doing here?” Runcorn pressed.

“Nothing to do with that,” Monk replied.

“There’s no need to be secretive now, Monk. She’s dead, poor creature.” He glanced down at her. “The only help you can give her is to find out who killed her.”

“I know that!” Monk retorted sharply. He steadied himself with an effort. “As I said, she was betrothed to Michael Dalgarno. She was concerned that there might be some fraud to do with the new line they are building between London and Derby.” He saw Runcorn’s start of interest. “Specifically to do with the purchase of land—”

“And was there?” Runcorn cut across him eagerly.

“None that I could find, and I looked very carefully.” Monk knew he sounded defensive. He felt it. If he had found the proof, Katrina might still be alive.

Runcorn looked dubious. “If it were plain to see, others would have found it too.”