To Harkness it sometimes seemed that every day was a separate evolution. He got out of bed speechless and breakfast was a thing of empty-eyed chompings and guttural grunts between him and his father, a kind of chimpanzees’ tea party. He progressed slowly, usually developing a brain about midday, and by evening he had re-evolved to polysyllables. Sometimes after midnight he was superman. That was why meeting Laidlaw at half-past eight in the morning was a bizarre conjunction, like a Neanderthal getting run down by a tractor.

‘We have to see Mrs Lawson. If it wasn’t Alan McInnes she saw, who was it? She uses Sarah Stanley as an alibi for her parents. She uses Alan McInnes as an alibi for Sarah Stanley. She was a complicated wee lassie. She probably went to the lavatory via Paisley. That big man has a lot to answer for. Imagine creating that depth of duplicity in your wean. So that she wouldn’t tell you the time of day in case you use it against her. Whatever game she was playing, it’s more involved than ludo. As far as our information takes us, there’s only one person, except for the man we’re looking for, who could possibly know about it. We have to see Mrs Lawson. In Mr Lawson’s absence. If that’s possible. I think he’s transistorised himself and crawled inside her head.’

Harkness nodded. He consoled himself with the thought that Laidlaw looked terrible, with a right eye like a road-map. It was maybe the result of the time-warp caused by trying to rush to humanity this early in the morning.

But Harkness had to admit it had an effect on him. Before they reached Drumchapel, he was having ideas.

‘See that place last night. In Byres Road. I’m just thinking about the big fella with the beard. I think you could catch them with pot if you went.’

‘Come on,’ Laidlaw said. ‘Every city’s got cancer. Who’s got time to clean their fingernails?’

They were lucky because while they were waiting at a bus-stop near the Lawsons’, hoping a bus wouldn’t come and deciding how they would go about separating Sadie Lawson from her husband, they saw Bud come out of the house and go in the opposite direction from them. The house still had its curtains drawn. It was the woman from across the entry who answered the door. When she heard what they wanted, she said she had things to do in her own house.

Sadie Lawson wasn’t so bad as when either of them had last seen her. The skin of both cheeks was abraded by her tears, but the tears had dried. She sat in a chair by the fire, which was cleaned and freshly set with coal but still unlit. The three of them sipped at the cups of tea the other woman had made before she went out. Mrs Lawson sighed a lot, waiting for them to approach her isolated grief.

‘I’m sorry,’ Laidlaw said. ‘But I need to talk about Jennifer. Not for very long. I know it’s sore.’

‘It’s a’ right, son,’ she said.

What she called Laidlaw was a status bestowed on herself by what she had been through. It gave her a kind of authority she had never had before and, exercising it, she simply started to talk without waiting for any questions. The way she spoke seemed at first to have the eerie irrelevance of a seance. But all the pieces cohered in a strange, hidden deliberateness. What she was all the time saying came to the one conclusion: how sorry she was to have sometimes supported Jennifer against Bud, to have sometimes gone behind his back, because this had been the result. She was to blame for some of it.

Harkness found her calmness more harrowingly moving than her tears had been, because he thought it meant something more terrible. That people should suffer such grief as she had had was difficult to endure, but that their suffering should only teach them how to lie to themselves, that was unbearable. And, watching her, he couldn’t hide from the conviction that she was burying her daughter in a lie, that, even dead, Jennifer was not to be allowed herself. Mrs Lawson’s confession was a subtle deception. She was like somebody who claims to be throwing down bricks without thought and is building a wall.

Her grief had developed a style and, genuine though it had to be, it had already acquired utility. Harkness realised that people often choose the guilts that they can handle. It’s a way of hiding from the truth.

‘Mrs Lawson,’ Laidlaw said quietly. She had paused. Harkness watched Laidlaw watching her and letting silence come like a cushion between what she had said and what he would have to say. ‘Jennifer didn’t go to Poppies on Saturday night.’

The silence ran between them like a fuse. Harkness saw her head come up and the eyes widen in disbelief.

‘Oh yes. She said she wis goin’.’

‘Was it only her father she told lies to, Mrs Lawson? She never told you any?’

‘Whit d’ye mean?’

‘Jennifer told you she was going to Poppies with Sarah Stanley. She told Sarah she was going on a date with a certain boy. She did neither. That’s two lies already, Mrs Lawson.’

‘Ah canny believe it.’

‘It’s true.’

‘She even lied to me at the end. Wait till oor Bud hears this next.’

She had started to cry.

‘I’m sorry, Mrs Lawson,’ Laidlaw said. ‘But Jennifer’s dead. And there’s not too much her father can do to her now.’ He paused. She rocked slightly, shaking her head. ‘And we both know that Jennifer had good reason to be the way she was. We both know that.’

She looked up at him. Her grief had become defenceless again and she looked frightened.

‘How d’ye mean?’

‘I’m talking about the Catholic boy she went with, Mrs Lawson. I’m talking about that.’

‘Whit Catholic boay?’

‘The one her father wouldn’t let her see any more. Did you know him?’

She stopped on the question. It seemed to be asking her much more than Laidlaw had meant. She hesitated, looked away, then was suddenly refusing to turn back.

‘Ah don’t blame her!’ Her eyes took in both of them as she said it, the most direct look Harkness had seen her give. ‘Ah don’t blame her at all. God bless ma lassie. Ah don’t blame her at all. Ah blame maself for no’ standin’ up for her mair. Why should she trust us? We didny deserve ’er trust. Aye, Ah knew about that boay. The wan boay she wanted tae go wi’. And he widny let her. She trusted me up tae that time. But Ah couldny stand up for her. Ah never could. An’ she never forgave me, God love ’er, she never forgave me.’

‘Did the boy ever come to the house?’

‘Are ye wise enough? Bud widny have that. Airchie Stanley telt him it wis a Catholic. Sarah let it slip. And that was it. We never got tae see the boay. It’s a funny thing, intit? It wis at that Poppies place that she’d met the boay.’

‘Mrs Lawson,’ Laidlaw said. ‘What was his name?’

She shook her head. ‘Ah don’t know. Ah never knew.’ She looked at Laidlaw steadily. ‘But Ah know who should know.’ Harkness watched her small crisis of daring with sympathy. It was her Martin Luther moment: here I stand. She wasn’t practised in courage but she found it. ‘Maggie Grierson! Bud’s sister could likely tell ye. Jennifer loved tae go there. Ah think it wis more her home than this was. Lives in Duke Street.’

She gave them the number, and Harkness saw why it had been hard for her to tell them. The rest had been only attitudes and so could be renegued on. This was a fact which they would follow up and Bud Lawson could hear of it. She had said something that she would have to stand by against her husband. It must have been a long time since she had done that.

The woman across the entry had asked them to fetch her before they left. While Harkness went for her, Laidlaw was still talking to Mrs Lawson, applying words like bandages. As they left, the woman was making her another cup of tea.

On the bus back into the city, Harkness thought Laidlaw was looking worse. His nose had started to run.

‘What’s up?’ Harkness said.

‘I think it’s what I hope it’s not,’ Laidlaw said. ‘Migraine. If we ignore it, it might go away. Mrs Lawson did a brave thing for her, didn’t she?’

‘She’s probably regretting it just now.’

‘I hope not. It looks as if that boy could be the one. We’ve got to get his name. A Catholic who used to go to Poppies. That won’t stand up in court. Funny how Poppies keeps coming back in. But that was where she didn’t go.’

Laidlaw put his hand up to his head.

‘Oh no,’ he said. ‘That’s the early warning system. Like somebody playing croquet with my right eyeball. In ten minutes I’ll have a head like a Borough Band.’

‘Nothing you can do?’

‘I’m sorry. You’ll have to go to Duke Street on your own. If you get the name, check it off with Milligan. I’ll have to go back to the hotel. And get my pills. If I catch it fast enough, I can contain it. If I don’t, it can take me a day to recover. Dear oh dear.’

Laidlaw spent the rest of the journey pressing his head as if he was trying to keep it from bursting. So much for rushing evolution, Harkness thought, but sympathetically.