‘And before you argue,’ Patrick added, ‘and start going on about rights and privacy and whatever, save your breath. This is a murder investigation. You might be the one in a million who thinks Denise is Snow White, but if the tabloids find out you tried to protect her, I don’t think you’ll have many clients wanting your helping hands any more.’

Walking out, Patrick felt no pride, just grim satisfaction. This, right here, right now, was the point in the investigation where the ends justified the means. The only thing that mattered was finding those kids.

They pulled up outside Freshtime Foods, a hangar-shaped architectural carbuncle based on the edge of an industrial estate in nearby Feltham. Patrick took off his sunglasses as he got out of the car, sweat prickling his armpits, the air thick and chewy. Carmella followed him into the building, appearing cool and fragrant as always, even as they pushed through the hanging plastic slats across the doorway into the stifling heat of the factory. Patrick had worked in a place like this once, during the summer holidays when he was a sixth-former, back at the height of his Goth days, when he always went out wearing make-up. He’d made the mistake of forgetting to remove his eyeliner before coming in to work one day. The meatheads who staffed the factory had loved that, giving him the nickname Rambo. Leaving that factory after a summer picking black cornflakes off a production line had been one of the happiest moments of his life.

A man wearing a foreman’s uniform approached immediately.

‘We’re looking for Denise Breem.’ As the foreman frowned, Patrick said, ‘She’s a temp.’

‘Wait here.’

The foreman walked over to the centre of the factory floor, where pots of jam were boxed and stacked on pallets, a group of women standing either side of a conveyor belt wearing blue and white caps and shapeless smocks.

‘That’s her,’ Carmella whispered.

Patrick squinted. Carmella was right. At the far end of the conveyor belt, down which pots of jam trundled, was the woman they were looking for. And at the same moment Patrick recognized her, the foreman spoke to one of the women, who pointed at Denise – and she bolted.

She ran towards the back of the factory and a row of huge cylindrical vats.

‘Come on,’ Patrick yelled, and he broke into a run, just as a forklift truck sailed into his path. He skidded to a halt, swearing at the man driving the truck, who lifted his ear protectors questioningly.

Ignoring him, Patrick and Carmella dashed around the back of the truck and ran past the conveyor belt towards the vats. There was no sign of Denise.

A door led out into a yard where dozens more pallets were stacked up. The two detectives went out into the bright sunshine. The yard was deserted.