Seed looked sickened. Even from a distance, in profile, through a crack between a door and its frame, his disgust was unmistakeable. ‘You’re not one of them,’ Simon muttered under his breath. ‘You’re never going to be one of them. So what are you doing here?’ He wasn’t expecting an answer, neither from Seed, who couldn’t hear him, nor from a supreme being eager to communicate with him confidentially, so he wasn’t surprised when he didn’t get one.

He went outside, hailed the first free cab he saw and told the driver to take him back to Muswell Hill. To Ruskington Road.

Charlie watched as the door to Seed Art Services opened with a slow creak. A few seconds later, Ruth Bussey burst out of the dark interior as if someone had shoved her from behind. She was wearing flip-flops on her feet. No socks or tights tonight either, Charlie noticed, and still limping. Charlie wondered again why anyone who hadn’t sprained their ankle would pretend they had.

She hurried over, wanting to catch Ruth before she got to her car, not caring if it was obvious that she was coming from the trees by the river, where she had no reason to be unless she’d been spying on the workshop. ‘Ruth!’

Ruth turned with a cry, then fell back against her Passat, pressing her hand against her chest.

‘I’ve been knocking and knocking,’ Charlie told her. ‘Since five thirty. But you know that, don’t you? You were in there all the time. Sitting in the pitch black with the door locked.’

‘I was thinking,’ said Ruth. Her voice lost itself in the biting wind that blew strands of hair in her face. ‘Trying to decide what to do.’

‘And did you?’

‘Yes.’ From her puffy eyelids and the chapped skin between her nose and upper lip, it was clear that crying had played a significant part in the decision-making process. ‘I wasn’t completely honest with you before, and it got me nowhere. I thought you’d laugh me out of the police station if I told you the full story.’

‘Where’s Aidan?’ Charlie asked curtly. What did the silly cow expect—a card saying, ‘Congratulations, you’ve stopped lying’?

‘I don’t know. I don’t know when he’ll be back. I don’t know much, but I’m willing to tell you what I do know, if you’ll help me. You’ve got to.’ Ruth grabbed Charlie’s arm. ‘He said he was going to kill her.’

‘What?’ A remark like that couldn’t be ignored, even if it came from the least trustworthy person on the planet, which Ruth Bussey might very well be, Charlie thought. ‘Who said he was going to kill who?’

‘Aidan. Mary. He called her “that bitch”. He’s not in Manchester—I rang Jeanette at the City Art Gallery. He wasn’t there last weekend . . .’