Jackie shook her head. “I can’t help it. I mean, if I’d just stopped to think about it for a minute, I would have realized that there was no reason on earth why Claire or anyone else should fall for her lies. But I didn’t stop to think. I should have been stronger, Lindsay. Then I’d have been out of there an hour or more before she was killed. I’d have had an alibi. Instead, I caved in and went to bed with her. You know what disgusts me most about myself? I actually enjoyed it. After all she’d said and done, I still loved every minute of it. Isn’t that sickening?”

Lindsay could think of nothing to say that would ease Jackie’s self-disgust. “It’s human,” was all she managed. “What happened then?”

“Alison started shooing me out. She said her mother was coming to see her and she didn’t want me wandering round with a just-fucked look on my face. So I got up and dressed in a hurry. I suppose that’s how I came to leave my scarf behind. Then I got out of there. I stood on the landing waiting for the lift, feeling like a complete shit. I didn’t want to go home. I couldn’t face telling Claire I’d been so weak. So I left the landing and started walking down the stairs, just to give myself a kind of breathing space. But my legs felt shaky, so I sat down and had a cigarette. Then I carried on downstairs, got into my car, and drove home. Mrs. Maxwell says she saw me, but I didn’t notice her. I was in too much of a state, I guess. The rest you know.”

Lindsay had listened to Jackie’s account with a growing sense of helplessness. There wasn’t even a loose strand anywhere she could start picking at to unravel this mess. “Didn’t you see anybody else at all?” she asked.

Jackie shook her head. “Not a soul. But to be honest, if a rugby scrum dressed in tutus had been dancing the cancan on the landing, I doubt if I’d have noticed,” she added with a touch of fire. “I was out of it, Lindsay, completely out of it.”

“Do you know who else Alison was sleeping with while she was seeing you?”

“I’ve no idea. Christ, Lindsay, you know how clever she was at keeping her secrets. She could have been screwing half of Glasgow and I’d never have known,” Jackie said with a swift, flash of her old liveliness.