It’s still only half eight in the morning and the temperature is cool for May. The storm last night has taken the muggy, oppressive heat with it, leaving a fresher wind that tugs at his jacket as he opens the heavy metal door and walks out onto the top level.

It’s indistinguishable from any other car park in the UK. White painted lines, a raised metal barrier round the edge. Robin can hear traffic on the road below, normal commuters, going to work on a Wednesday morning.

There are people everywhere. More blue-and-yellow patrol cars are parked, creating a cordon, and crime scene tape has been stretched between them. In the centre is a large silver van, sideways on, with the BBC logo emblazoned across it. It looks like a long-base Transit: driver’s cab at the front, one square clear window on the side, large double doors at the back. Odd-looking technical equipment, including a large, white satellite dish, is secured to the roof. It seems big, too big for its surroundings, and Robin wonders briefly how they got it up there. Everything is quiet.

Robin makes his way towards the crowd of uniformed officers and detectives in plain clothes. As he approaches, the whole group hushes, and a short, boyish-looking detective taps the arm of a woman standing next to a fold-out table in the centre. She looks over from their makeshift operations centre; Robin attempts a smile but it comes out as a grimace.

‘You must be DS Butler,’ the woman says. She’s tall, with long, poker-straight hair tied back in a severe ponytail at the nape of her neck.

Robin nods. ‘DI Craig?’

‘Hoping you can shed some light on this mess,’ she replies bluntly.

Robin hadn’t expected pleasantries. It isn’t common for a detective to be welcomed onto another constabulary’s crime scene, and he can only assume they’ve tried a number of possibilities before calling him.

‘What’s going on?’ he asks.

Craig looks towards the van.

‘We believe there are two people in there – your friend Finn and his colleague Dr Simon Sharp. From what we’ve been told,’ she says, gesturing towards a group of nerdy-looking men on the far side of the car park, ‘they were parked here last night to record the storm.’

‘Just the two of them?’

Craig shakes her head. ‘No, there was a cameraman, but he left the van early to pick up extra equipment. The storm swept in quicker than expected, leaving Mason and Sharp in the vehicle. Since then, nobody’s been able to gain access.’

‘And why were the police called?’ Robin asks.