“Of course. But still...” she said with a tiny skip of excitement, and Aaron had to repress a smile. He remembered being a DC, feeling like that. It seemed rather a long time ago.

Mr. Marks had lived not far from his office, on Bunhill Row. The door was opened by a thin, tired woman. “Yes?”

“I’m Detective Sergeant Fowler, and this is Detective Constable Challice, ma’am.”

Her expression clamped instantly shut, though he’d seen that often enough not to draw conclusions. “What is it?”

“Is this the residence of Mr. Gerald Marks?”

“Yes.” She glanced between them. “He didn’t come in last night. Has something happened?”

Her name was Mrs. Trotter. She insisted on tea, reminding Aaron of Wildsmith’s almost resentful offer of the beverage, and waving away Challice’s attempts to make it, and then took off her apron and sat, hands wrung together, face pale.

Marks had been with her for ten years, she said. He was a good tenant but times had been tight over the last couple of years. “He was short a few times, but I trusted him. He paid me on time for this month, and my back rent, too. He always did when he could.”

“Had he a new case?” Aaron pressed. “A new client?”

“He didn’t talk to me about his work. A private detective must keep things private, he used to say, and quite right too.” She snapped her mouth shut illustratively.

“True. But unfortunately we do need to ask questions, so if you know anything—”

“Why?” she interrupted. “What happened to him? You said detectives. Was it—did someone—”

“We don’t know exactly what happened yet. It might well have been an accident, but we have to make sure.”

“Do you have any reason to suspect someone meant him harm?” Challice asked.

Mrs. Trotter drew back. “Well, he had a funny sort of business, didn’t he? That’s what he said. People hire you to ask questions other people don’t want asked.”

“Same as us,” Challice remarked, with a winning smile.

“Not on Mr. Marks’ saying,” Mrs. Trotter retorted. “He said there was plenty of questions the police didn’t want asked.”

“What sort of questions?” Aaron asked.

“I don’t know. It wasn’t my business.”

She was clamming up; he could feel it. “Of course he couldn’t talk idly about his clients,” he said, trying to sound approving. “Sounds like he knew his stuff. What sort of cases did he mostly do? I tend to think of private detectives as mostly lost dogs and divorces, but perhaps that’s not fair.”