Hanson had played it perfectly, however. She’d requested the search, and been calm and collected giving her evidence to the magistrate via video link. She hadn’t even mentioned the blood. Instead she had explained that Louise had previously lied about her whereabouts that night. She had then expressed concern over Louise’s reaction on arriving back at the house. Vomiting, she felt, was likely to have been the result of guilt or anxiety.

The magistrate had agreed.

Hanson had asked to be there while the search took place, and Jonah had been more than happy to bring her along. If they ended up making an arrest, he wanted Hanson to have the satisfaction of doing it.

It was hard not to feel a little sorry for Louise as they converged on her front door, however. Her neighbours were unlikely to forget this particular scene. Though at least the front of the house was fairly well screened. Louise herself wouldn’t be on full display.

Jonah knocked loudly, reverting to the loud rapping they’d been taught when he’d first become a constable. Knocking that was too loud to ignore. Too loud for ‘I didn’t hear you’. The kind of knock used only by policemen or bailiffs.

Louise’s eyes were very wide as she opened the door. She said nothing as Jonah showed her the warrant and told her that they had the right to search the property. She did no more than nod, and then move slowly aside.

Janet McCullough had already been primed to search the bedroom. She left three of her overall-covered team downstairs and headed upwards with just one of them. Jonah gestured for Hanson to follow them, while he prowled around downstairs. Louise retreated to the far end of the house, and Jonah left her to it for now.

What was to follow was both thorough forensic work and a little play-acting. They had to let a reasonable amount of time pass for it to look like the blood had been discovered organically. So Jonah drifted in and out of rooms, asking the three forensic staff to look at a few things. A faint mark on the wall next to the stairs. The laundry hanging out on a rack in the tiny utility room.

McCullough left it fifteen minutes before she called him upstairs. Jonah was in the music room at that point, where Louise was sitting with her legs pulled up on a futon. In that position she was largely hidden behind her harp, but he could still see the side of her face through the strings.

It was clear from her expression that she knew what McCullough had found. Her legs moved instinctively, as if she were about to get up, before she froze in the act and tried to sit back naturally.