Sasha drove with the top down on her Spider Veloce, taking the A13 to the edge of Southend where the former garrison town of Shoeburyness sat at the mouth of the Thames estuary. It was only a short journey, but it was a relief to get out of the office and enjoy the wind in her face on another blazing hot day.

‘Put this on.’ She offered Craig a floppy hat imprinted with flowers. Sasha knew how easy it was to get burned on the top of the head driving about under the hot sun, and had taken to wearing one herself. ‘Go on.’

He took the hat and placed it on his head, morosely adjusting it in the side mirror, but whipped it off almost immediately.

‘I can’t,’ he said, and she knew he didn’t want to look uncool.

‘Suit yourself,’ she told him, pushing her sunnies up her nose.

The caravan park was buzzing when they got there. It was the height of the season and was packed. As Sasha parked – the suffocating heat enveloping the vehicle as soon as she cranked the handbrake – she saw kids screaming and splashing about in a swimming pool outside the main building. The glittering aquamarine water danced and leaped as the children cannonballed into the middle of the pool or fought for ownership of the lilos that ricocheted about on the surface. The area around the pool – the concrete surround and the faded brown lawn – was full of holidaymakers slathered in sun cream and walking about in bikinis and trunks and flip-flops. They sat in fold-up chairs staring at their phones, or sprawled on sunbeds.

In every direction were rows of caravans. There were long static ones the size of small homes, with porches and pot plants, and some had little white picket fences around them, with tiny gardens of fake grass; and there were tow caravans of all shapes and sizes, short and stubby, long and thin.

The snaking silver hose of a portable air-conditioning unit poked out of the door of the reception building. The unit made a lot of noise, as if it was working hard, but it was still as hot as a sauna inside. Sasha’s skin was damp at the hairline from where she’d worn the hat, but Craig looked like he’d been dragged through a blast furnace, and he walked straight out again, saying, ‘I’ll wait outside.’

She brought the heel of her hand down sharply on a small bell and a thin, harassed-looking woman appeared from a small office behind the desk.

‘I’m sorry, we’re full,’ she said in a voice that suggested she wasn’t very sorry at all.

‘Detective Inspector Dawson, Essex Police.’ Sasha placed her warrant card on the counter and pushed it towards the woman. ‘I’m looking for Stephen Gosling.’

‘You mean Steve Gosling?’

‘That would be him.’ Sasha smiled. ‘I understand he works here.’