‘Did anyone apart from Seed have a reason to want Crowther dead?’ Simon asked.

‘I can’t answer that,’ said Milward, tipping Simon an easily deniable nod. Had he imagined it?

‘The boyfriend, Stephen Elton—why didn’t he go home with Crowther after the Quaker Quest meeting? They lived together. If he stayed behind to clear up, wouldn’t Crowther and Len Smith have waited for him, so that they could all go back together? Were Seed and Crowther having an affair? Did Elton find out?’

Milward folded her arms, waiting for the questions to stop.

‘What was Stephen Elton doing between the end of Quaker Quest and midnight? It wouldn’t take him two hours to clear away some chairs and get back to Muswell Hill at that time of night.’

‘Wouldn’t it?’

‘You don’t know where he was all that time,’ said Simon. ‘You like him as a suspect—it’s usually domestic if it’s not drug- or gang-related. So he also had a motive to kill Crowther, did he?’

‘Excuse him,’ Charlie said to Dunning. ‘He gets carried away.’

‘I’m interested in hearing all you can tell me about Seed.’ Milward had started to behave as if she and Simon were alone in the room. ‘You’ve met him. We haven’t. Forget about his car being outside Gemma’s house, forget about his being at Quaker Quest and using a false name—what can you tell me about him as a person? Is he a killer?’

‘We don’t know,’ said Charlie. ‘Simon doesn’t know.’ Was there a note of satisfaction in her voice? ‘He told us both he’d killed a woman who’s still alive. His girlfriend seems intermittently scared of him, though she’s insisted several times that he wouldn’t hurt her or anyone else. We’ve told you all this . . .’

‘I believe Seed’s a killer,’ said Simon. ‘All right, I don’t know. But he described a murder to me in vivid detail—too vivid to be invention, I thought when I heard it. Mary Trelease is alive, though, which means Seed’s also a liar, unless he’s crazy. If he is a liar, he’s the best kind.’

‘What kind is that?’ asked Milward.

‘One who blends lies seamlessly with the truth and counts on you spotting the truth but not the join. He killed another woman, maybe more than one, before he killed Gemma Crowther. He might still kill Ruth Bussey and Mary Trelease, which is why you need to find them.’

‘Aidan Seed the picture-framer. The two of you visited his picture-framing workshop on Monday afternoon.’

‘Why do you keep saying that?’ Simon asked. ‘Are you suggesting he isn’t a picture-framer?’

‘What about this photo you wanted to show us?’