‘Oh, come on.’ I could hardly believe I was hearing this. ‘Marlon and Herschel are smart guys. They’d never get involved in crap like that.’

When I thought of Herschel, I thought of someone quiet and introspective and calmly intelligent. Marlon, like Floyd, was from the American South. He was the first in his family to go to university. When I thought of cults, I thought of glassy-eyed drones in matching jumpsuits, or wild-eyed Charles Manson types roaming the desert in pickup trucks looking for victims.

‘Smart people are just as likely as anyone else to wind up in a cult,’ Floyd insisted. ‘And smart people aren’t always that good at reading other people. Maybe they get lonely, or they lack certain social skills, or maybe they’ve got the kind of spiritual questions they don’t think they can get the answers to from a church.’ Floyd leaned back, tapping a finger against his coffee cup. ‘After that, it’s the proverbial long, slow slippery slide into believing the craziest shit. Intelligence has nothing to do with it.’

‘What’s going on, Floyd? Why are you even telling me this?’

‘Were you aware GreenTech is about to be the subject of an external audit?’

I looked at him, stunned. ‘I had no idea. How do you know?’

‘I work for the government,’ he said.

‘Yeah,’ I said. ‘Somehow I’d figured that.’

‘I know a lot of things about the work GreenTech does,’ he continued. Then he rattled off a list of current projects, some of which I recognized, partly because my employers had required me and everyone else working at the facility to sign a number of frankly punitive non-disclosure agreements. Hearing those projects even named outside a lab environment made my heart freeze.

‘Just to be clear,’ I asked, only partly joking, ‘which government?’

He smirked, then pulled out his wallet and showed me his Central Intelligence ID.

‘You were a maths major,’ I said. ‘How the hell does a maths major . . . ?’

‘Codes and ciphers,’ he replied. ‘And that’s all I’m saying on the subject.’ He put his wallet away. ‘Maybe if you help me out, I can shield you from the fallout that’s going to come from that audit. Because, believe me, it’s going to be a bitch.’

‘I haven’t done anything wrong,’ I said, hating myself for whining.

‘Dirt clings to the guilty and the innocent alike,’ Floyd said. ‘All I ask is that you keep an eye on Marlon and Herschel.’ He scribbled some numbers on a napkin and pushed it over. ‘And call me if you see or hear anything that strikes you as odd.’