‘Finn’s best friend,’ Craig clarifies. ‘Not here in an official capacity, but you can talk freely in front of him.’

The doctor nods sternly. ‘I’ve done as you asked, DI Craig, and my assessment today is the same as when Finn came in on Wednesday.’ Robin looks from Blackstone to Craig, confused. ‘Finn Mason is not fit to be interviewed by the police.’

Robin scoffs. ‘Of course he’s not.’

Craig glares at Robin but stays silent.

The doctor continues, ‘Yes, he has the ability to understand the nature and purpose of the interview and to appreciate the significance of being questioned by the police.’ He takes a sip of his coffee, regarding them with dark, heavy-lidded eyes. ‘But his current mental and physical state means that there is no way he can be accurate or tell you the truth.’

Craig glances to Robin. ‘Is he faking?’ she asks.

‘Piss off!’

But the doctor ignores Robin’s outburst. ‘No, I very much doubt it. Initial results from the MRI on Finn’s brain shows swelling in the prefrontal cortex, which would tie up with his memory problems. He can’t remember what happened, even if he has the correct functional ability to tell you.’ Blackstone finishes his coffee with a flourish. ‘The craving for alcohol alone affects his reliability and makes him mentally vulnerable. So no, detective, you can’t interview him.’

With a final nod, he leaves them alone.

Robin turns to Craig. ‘Really?’ he asks, disbelieving. ‘You honestly thought the doctor would say yes?’

She sighs. ‘No, of course not. But the medical opinion gets my chief off my back.’ Her phone starts ringing. She pushes her chair away from the table and stands up.

‘Here he is now. If you’ll excuse me, Robin, I need to speak to my DCS before he has a coronary.’ She looks at him sympathetically. ‘Go and be with your friend, Butler. Step away from being a copper for a change.’

Robin watches her go. He finishes his coffee, then, his stomach growling, he picks up the leftover slice of her toast and eats it quickly. He hasn’t had time for breakfast either.

He does as he’s told and walks up the stairs to the ward where Finn is being treated. He moves slowly, in no rush, keen to digest the information about the case.

It simply isn’t possible for him to stop being a copper. It’s built into his bones; nearly twenty years of police work has it hardwired into him. And he knows it isn’t looking good for Finn.

He has motive: the argument with Sharp in the days before the storm. Means: the penknife found in the van. And the opportunity: he was the only other person there. Post-mortem confirms Sharp’s death was most likely an unlawful killing, and Finn’s own confession in the van gave the likely culprit.

What else could Robin possibly do?