Emerging above ground, my eyeballs throbbed as they adjusted to the glare of the sun. We were in a small clearing surrounded by dense forest, deserted except for two vehicles: a dirt-spattered Land Rover with a large red cross on its side and a white Mercedes estate in which were seated several heavily armed soldiers, all of whom were watching us keenly.

‘Akuji’s men?’

David nodded.

I got him to hand over the keys to the Land Rover and told him to wait for me.

There were six of them, all seated in varying postures designed to intimidate, all in crisp uniforms with the Biafran sun on their shirtsleeves and berets sitting on their heads at the correct angle.

‘Hello,’ I said. ‘I’m Doctor Foster.’

‘Where is the Colonel?’ said one of the men, his thumb toying with the trigger of his machine gun.

‘He’s still downstairs,’ I said. ‘He wants to talk to the patient some more. Doctor Kanu and I are needed elsewhere, so he asked me to tell you to wait here for him.’

A few of the men sighed or rolled their eyes.

‘I’m sorry,’ I said. ‘He should be up in about half an hour.’ David had told me that all the patients below ground had been moved to another clinic on my arrival. But they didn’t know that, and I reckoned it would be at least another hour before they ventured downstairs to check up on Akuji. I turned to walk away.

‘Doctor Foster!’ one of them called out. I turned to face him and smiled through clenched teeth. ‘Are you from Gloucester?’ he asked.

A couple of the others broke into laughter, no doubt remembering the rhyme from childhood. Careless, Dark: you may be in the middle of the bush, but it’s also a former British colony. If you’re going to make this cover work, you’re going to have to use your head a bit more.

I smiled wearily. ‘Very funny,’ I said. ‘I’ve never heard that one before.’

Their cackles followed me back to the Land Rover. David was already behind the wheel, so I climbed in and handed him the key. As he started the ignition, he gestured at a small plastic container on the dashboard, which looked to be filled with yellow mush.

‘Garri,’ he said. ‘Crushed cassava.’

I told him I wasn’t hungry.

‘That’s because Benzedrine suppresses the appetite. But your body needs this. Eat.’

I did as I was told. The taste was coarse and bitter, but I was soon using my fingers to scoop out the last of it. When there was none left, I laid my head against the window and watched the landscape judder by.