“No notebook or any other record dated from the last three months.”

“Perhaps he hadn’t had any cases recently. Or perhaps—”

Their eyes met. Aaron said, “Let’s have another word with Mr. Gillan.”

The landlord had refreshed himself while they were engaged in the office: the smell of gin was pungent.

“Did Mr. Marks have many clients?” Aaron asked him.

“Not so I saw,” the landlord said without interest. “Not my affair.”

“Was he busy in the last few weeks?”

“Dunno. Well, he must have earned something because he paid his back rent and this month’s on time, no fuss, and that made a nice change.”

“He’d made money. Any idea from whom?”

“How should I know?”

“Have you a home address for him?”

Gillan found a ledger with the required information. As Aaron copied it down, Challice said, “Was he working here yesterday?”

“Nah, didn’t come in at all,” Gillan said. “Just last night.”

“He came here last night?” Aaron repeated. “What time?”

“I dunno. Midnight? Two?”

“Did you let him in?”

“Course not. He had keys.”

Aaron and Challice glanced at one another. “Did you see Mr. Marks come in yourself?”

Dogged questioning elicited that Mr. Gillan slept in a small cubbyhole to one side of the entrance hall. He had been vaguely roused last night by the front door opening, and someone going up to the first floor who must have been Mr. Marks because the other office was unoccupied. Mr. Gillan had not thought it necessary to get up and check. The individual had gone upstairs, stayed there for an unspecified time, and left, not troubling anyone on the way in or out.

“What did you think he was doing in the middle of the night?” Aaron enquired, and got only a shrug. Irritated, he added, “Do you not feel it your job to protect tenants from burglars?”

“What burglar? He had a front-door key, didn’t he?” Gillan said, taking offence. “Marks’s office was locked when we came up, wasn’t it? So what’s the problem?”

“A private detective with a nasty head wound in the canal,” Challice said, as they strode out of the stifling little building. “A new gold watch still on his person, and he’d been able to pay his rent recently. No keys on him, someone got into his office last night, and the records of his recent private detection are missing. Ooh.”

“Hold your horses,” Aaron said. “We’ll need a look at his home before we conclude the books are missing. And I’m not placing a lot of reliance on Gillan’s testimony. I wouldn’t like to put that fellow on the stand and have a defence brief demonstrate that he can’t tell last night from last month.”

“True,” Challice agreed, deflating slightly. “You don’t think he saw someone?”

“I’m reserving judgement till we see if Marks’s notebooks and office keys are safely at home.”