I’d worked out how to ask Marcel whether his lead had any news of my parents, but Amelia got there ahead of me. My optimism stalled in the pause before he answered her, the light feeling in my stomach hardening into a fist. He was sorry, but no, he eventually said. He’d not been able to track down the guy he was sure Yannick would have used. However, he’d also done some research into Langdon’s mining interests. They were spread far and wide, but by far the biggest project was a flagship modern operation, called the Canonhead Complex, just to the west of the national park.

‘Modern?’ I asked Amelia as much as him. ‘Surely all mines are pretty modern these days.’

Marcel understood my question but his lengthy reply went over my head. Amelia could see I was lost. ‘He says not at all. The vast majority of mining in the DRC, whether it’s for tantalum, cobalt, or any precious metal, even gold, is done by hand with picks and shovels. It’s incredibly dangerous, brutally hard work, and the miners who do it are paid a pittance. At least half of their work feeds a government-backed black market. They sell what they mine for virtually nothing to traders who sell it on to bigger companies who export it to the West and China. So a modern, mechanised, well-regulated mine is an exception.’

‘And that’s what Langdon’s doing?’ I said. ‘If so, it’s pretty impressive.’

Marcel snorted, hearing that. ‘Toute en face,’ he said.

‘That means on the face of it,’ Amelia said, though I’d kind of guessed that.

The truck was rattling along a potholed road now: I realised I had no idea where we were going. It seemed sensible to ask. Marcel again replied at length. I tried to follow but he talked quite fast. I caught the words rivière and oblique, but couldn’t piece his meaning together.

Amelia translated: ‘Marcel here has done some digging,’ she said. ‘No pun intended. Apparently your mum and dad were headed to this Canonhead place a few days ago. So it makes sense to start the search there. It’s where Caleb is working too. Trouble is, to get anywhere in among the mines requires a whole load of paperwork, permits, vehicle checks and so on. Langdon cut through the red tape for Caleb, but we’re going to have to be a bit more cunning.’

‘Cunning how?’

‘Marcel’s thought it through. We need to take an oblique route. That means indirect.’

Sometimes Amelia takes me for an idiot. I dug my elbow into her side and said, ‘You don’t say!’

‘Sorry,’ she said, returning the prod with her own elbow just below my ribcage. ‘Just trying to be clear. Anyway, he’s lined up motorbikes.’