‘I don’t think it goes boom. It takes at least twenty-four hours from when you fill the drill holes to when the stone cracks. Perfect if you don’t want to be anywhere near the crime scene.’

Karen starts the car and lets her mind wander while she drives back down the tree-lined driveway. That a member of the Groth family would have vandalised the ship setting sounds implausible. After all, the stone ship must be an important component of their pitch to attract tourists to Noorö. On the other hand, Fredrik Stuub may well have thought they’d be willing to go to such lengths to save a few million and acted accordingly. The question is why he would decide to email Björn Groth rather than go to the police. Or the media. If he had really wanted to stop the expansion, either would have been a more effective way of spreading rumours and tainting the project.

‘Maybe he wasn’t such a dyed-in-the-wool idealist,’ Karl puts in, apparently thinking along the same lines. ‘Maybe the old man was trying to squeeze money out of the Groths.’

‘If he even knew about the bags of cement. It might have been about something else entirely.’

Karl makes no reply. Just as Karen turns on her indicator to merge onto the motorway, the memory that has been lurking at the back of her head resurfaces.

‘Expansive cement,’ she says, slapping the steering wheel. ‘Of course! It must be the same thing.’

Karl has pulled out his phone and is writing a text. To Ingrid, Karin assumes. Their twins hadn’t even turned two when a third child joined the Björken family and Ingrid is no doubt less than pleased that her husband has been called back to work before finishing his parental leave. I wonder what Smeed said to talk him into it, she thinks to herself.

‘It goes by different names,’ Karl replies distractedly while he types. ‘Some call it Type K, but I think that might be a particular kind. Why?’

‘Fredrik Stuub’s browser history. He did a search for expansive cement.’

Karl slowly puts his phone down and turns to Karen.

‘So, bingo, then, I guess,’ he says. ‘We’ll have to talk to Groth again. Do you want to head straight there?’

‘No, let’s hold off on that. He’s won’t talk to us again without a lawyer.’

‘Can it really wait until Monday?’

Karl fails to hide a note of hopefulness in his voice.

‘You go home,’ Karen replies calmly. ‘The Groths aren’t going anywhere. I can bring Byle in if it becomes necessary to talk to them tomorrow.’

‘So you’re staying?’

‘To be honest, I’m too tired to drive home. I rack up enough miles driving up and down this damn motorway.’

‘It’s a beautiful island,’ Karl says with a grin. ‘But bloody long.’

Just then, Karen’s phone rings.