Between the two of them they plot Miller’s movements onto a whiteboard. Freya reads from the car telematics and adds them to the iPhone details they have: Friday night, and King’s Wine Bar in town for Khalid Riaz’s fortieth. Home, via a brief stop on Jewry Street. Waitrose on Saturday. Then a walk along the River Itchen. Phone call to Domino’s Pizza at 19:15 Saturday night. To the municipal tip on Sunday morning. Working from home Monday, then the hotel, where he, and his phone, stayed until Robin picked it up and entered it into evidence on Tuesday.

Freya prints out the photos from Twitter and sticks them on the board. There is nothing here that raises a red flag. The satnav in the car matches the geotagging on the phone. Even a few searches on Google seem to correspond: late Sunday night he types in what is erotic asphyxiation? And follows it up with a few videos on YouTube. Then: what do you need for auto-erotic asphyxiation?

‘Bloody quick learning curve,’ Robin remarks to Freya.

‘Hmm?’ she replies, her back to him, staring at the board. She’s still distracted, hardly listening to him.

‘West?’ he says, and she turns. ‘Should you be here?’

‘Yes, yes, sorry, Sarge. I’m fine,’ she blusters, then adds a few actions to their list. Follow up with Domino’s Pizza, chase forensics on car, interview neighbours to check movements.

She puts the marker pen down, then grabs the bottle of water on her desk, taking a desperate swig. Robin eyes her warily. Hangover? he wonders. But it’s something he’s done on more than one occasion, and he lets it go.

He’s seen her around the station many times before. Chatting, laughing with other DCs, swinging that mane of blonde hair around. Since she’s been working for him, she’s been silent. Sullen even. Is that his effect on people, Robin thinks, even after one day?

‘So, what?’ he says, trying to get Freya’s attention again. ‘Miller googles erotic asphyxiation on the Sunday night, then decides to try it on the Monday? Wouldn’t you want to give it a bit more thought before you choked yourself in a hotel room?’

Freya cringes at his words. ‘Perhaps somebody mentioned it at the party on Friday night,’ she suggests.

‘That would be quite a topic of conversation,’ Robin replies. ‘Although who knows what these banker types talk about after a few glasses of champagne.’ He remembers the list of guests provided by Amy Miller and passes it across to Freya without looking at it. ‘Follow up on these guys. And the sister for the alibi from Monday night.’

He adds another note on the board: Interview Khalid Riaz.

‘We’ll go tomorrow,’ he says, drawing her attention to the last action. ‘Give him a call, set something up, will you?’