Abberton. Framed, signed, dated 2007. I forced myself to close my eyes, then open them and look again, to make sure it was real. I walked towards the picture, seeing nothing else; it might have been the only thing in an otherwise empty room. Now I understood why the name of the woman Aidan said he’d killed had sounded familiar, even though she’d never introduced herself to me. I’d done plenty of paperwork for Saul; I’d probably sent her a bill or a receipt, or seen her name on one of the ‘Work Pending’ lists Saul used to pin up everywhere.

That same name was painted in neat black letters in the bottom right-hand corner of the painting in front of me: Mary Trelease.

It took me about four seconds to realise that if Mary Trelease had painted Abberton in 2007, Aidan could not have killed her years ago. He’d made a mistake. I felt myself swell with relief. Of course he wasn’t a killer. I’d known that all along. All I needed now was to find him so that he could see the picture for himself, but the woman from the TiqTaq Gallery had said she’d seen him heading for an exit. What if he was in a taxi on his way to King’s Cross?

I was unwilling to move from TiqTaq’s stall. I knew I couldn’t let Abberton out of my sight. It was my evidence—indisputable proof that Aidan hadn’t done what he thought he’d done. It occurred to me that there might be more than one Mary Trelease, but I quickly dismissed the idea. Even if there were dozens or hundreds of women with that name, the artist who had assaulted me in Saul’s gallery had to be the one Aidan thought he’d killed. She was a painter; he framed pictures. They both lived in Spilling. It couldn’t be a coincidence. Perhaps they’d had a fight. She might have attacked him—a hypothesis that seemed entirely consistent with what I knew of her character—and he’d defended himself . . . My mind raced ahead, going through the possibilities, but I couldn’t focus on anything for long. Shock was still slamming through me and I couldn’t think coherently.

‘I need to buy a painting,’ I said to the woman with the dyed hair. ‘That one there.’

She shrugged. If I wanted to forget about the man I’d been looking for and boost her profits instead, that was all right by her. ‘Great,’ she said, though her tone and manner conveyed little enthusiasm. She hadn’t looked to see which picture I’d pointed at. ‘Let me dig out the relevant forms.’ Languidly, like someone with all the time in the world, she bent to open a desk drawer.