I wanted to take stock, see if there was anywhere we could hole up and watch Langdon’s house to monitor who came and went. But aside from this tree there was little cover. We could fake-tinker with the bike for a bit, but do it for too long and we might arouse suspicion. My head was heating up within the helmet, which smelled of someone else’s sweat. How could we keep an eye on Langdon’s house without running the risk of being caught ourselves?

I’d asked that last question of myself silently, or at least I thought I had, but either I’d muttered it aloud or Amelia was thinking in time with me. ‘Easy solution,’ she said.

‘What?’

‘We should split up. There are no turnings off this street. It joins the main road at either end. Drop me off at the southern junction and take the bike to the northern one. We’ve got phones. If that truck leaves, one of us will see it, and if you move fast, we’ll be able to follow it. The bike will be much quicker than a truck through traffic.’

It seemed risky – what if I was too slow and we lost him? – but I couldn’t think of a better plan, so we did as Amelia suggested and positioned ourselves at either end of Langdon’s curved street. Amelia had an advertising hoarding to hunker down behind at the southern junction. To the north, where I was waiting, there was a mechanic’s. I parked the bike to one side of the forecourt behind a truck of threadbare tyres, and waited, and waited, and waited. The storm had long gone and now the sun came out. I sheltered in the shade cast by the truck’s cab. The shade moved. I went with it. In time it shrank to nothing on my side of the truck. I waited there sweating as the afternoon wore on towards evening. Just as the light was fading – and my hopes with it – my phone, which I’d had in my hand the whole time, burst into life.

‘This end! Now!’ Amelia said when I picked up.