‘I’m genuinely sorry, Karen, but you brought this on yourself. You shouldn’t have dragged my son into this.’

You’re the one who dragged him into this, she retorts inwardly. You manipulated your own son into creating an alibi for you. ‘Accidentally’ dropped his phone into the toilet so he had to borrow yours. Made him promise to call his mother from Lysvik while you were at the quarry. And your visit to your poor old dad can’t have lasted more than five minutes, rather than the hour you claimed you spent with him. Fucking psychopath. How did I bloody miss it? The grandiose self-image, the feigned humility, the charm. The ability to dupe the people around you, the compulsive talking. It was all there.

And with mounting horror, she recalls the number one characteristic of a psychopath: the inability to feel empathy.

Out loud, she says, ‘Why did you do it? What’s in it for you?’

‘What’s in it for me? Everything, obviously. The Groths don’t stand a chance of getting the expansion approved in time to pay their creditors. The provincial board won’t stand for it. Alzheimer’s is the bogeyman of our time, well, Alzheimer’s and cancer. The slightest hint of suspicion will be enough to make the politicians pull the emergency brake.’

Suddenly light-headed, Karen staggers slightly. Without asking permission, she walks over to the table and sits down on one of the chairs. William watches her impassively.

‘But why kill Fredrik? He was the one who did the research.’

‘Because he refused to publish, of course, said the results hadn’t been verified. I just wanted him to go public with what he had, it would have been enough. But the old git refused.’

‘But he did send Björn Groth a threatening email,’ she says, hoping he’ll take the bait.

Pretend you don’t understand, she tells herself. Play dumb, stoke his vanity. Make him feel smart. Stall.

He chuckles.

‘Wrong again. Technically, Gabriel sent that email. He knew where the old man kept his laptop – Lord knows I looked everywhere before I asked for his help. But Gabriel wasn’t exactly difficult to persuade.’

And then you put the laptop back in the concealment to make us think Björn Groth had been there to look for it but hadn’t found it, she thinks to herself. You have no idea how close we came to missing it ourselves.

‘When did Fredrik figure out what you’d done?’ she says instead.

‘When Björn called him. Fredrik was furious, of course, since he knew he hadn’t sent any threatening emails. But eventually he put two and two together and realised it must have been me. I’d been trying to talk him into publishing for months. On Christmas Eve he pulled me aside at Gertrud’s house, demanded that I talk to Björn, or he would. It was an unsustainable situation.’