In the middle of their rear seat sat their delightful, twenty-eight-year-old Californian nanny, Kaitlynn, who had become something of a family friend. She was sandwiched between Bruno and their two-year-old son, Noah, in his child seat. Roy and Cleo had offered Kaitlynn and her boyfriend, Jack Alexander – a Detective Sergeant on Roy’s team – a free holiday. In return she would occasionally look after Noah while he and Cleo went out on some of the long bike rides they’d been looking forward to.

So far as he could tell, Kaitlynn had spent the entire journey either texting or Snapchatting or playing games on her phone. She’d also said that she’d been trying to call Jack to see if he’d arrived safely, but hadn’t had any luck getting through to him.

The rain got worse. This was France, mid-August, and a week of solid sunshine was forecast. So far, not a great start. Cleo peered at the map on her phone, also trying to find the road – she’d been trying for ten minutes now. Rue de Joigns. Then she shouted out, ‘Got it! About three kilometres ahead! The directions the chateau gave us say to turn left off this road, then the entrance will be four kilometres along on the left and we can’t miss it.’

‘Brilliant!’ Roy said. ‘Well done, finally! Please God they can give us something to eat, I’m starving.’

‘We all are,’ Cleo said.

Roy glanced at the clock – 3.45 p.m. ‘Try calling them again, just so they know we’re only minutes away.’

‘Roy, I’m sure if Jack’s already there he’ll have asked them to keep some food for us,’ Kaitlynn said. ‘I’ve texted him as I can’t get through on the phone, to tell him that.’

Jack had had to go to Paris yesterday to take a statement from two French police officers for one of Roy’s cases that was coming to trial. He was going straight from Paris to the chateau, a 200-kilometre drive, and should have been there by midday.

Roy and Cleo had planned to arrive by 1 p.m., to give them time to enjoy their first afternoon on holiday. But the early-morning Newhaven–Dieppe ferry had been late. Then the satnav had taken them way off track, making them even later. They’d tried calling the chateau several times. Each time all they got was crackle and a faint voice shouting, ‘Bonjour . . . bonjour . . . hello?’ Then the phone would go dead.

As Cleo dialled yet again, Bruno announced, reading from his iPad, ‘Papa, Mama, listen!’

‘Yes, Bruno?’ Cleo said.

‘It says that next to being in a car, this is where you are most likely to die. Guess where?’

‘In an aeroplane?’ said Cleo, who did not like flying.

‘Wrong!’

‘Your kitchen,’ Roy Grace said.