It showed two men in the unlit room of a derelict squat. Both were white. Both were under thirty. One wore a zipped-up S-and-M leather hood and was naked to the waist. The camera sat steady on him as he took some time to prepare tools and show them to the camera. This man was twenty-nine. The other man was also naked to the waist, but he hadn’t chosen to be dressed like that. He was unconscious, drugged and lying strapped to a bench. He didn’t move. Not until the hooded man moved the hacksaw to his neck. Then he moved. He moved a lot. He was just nineteen.

This video was infamous throughout the force. The press knew it existed and would have done anything to get a glimpse of it. It showed the death and near decapitation of Jonah Dundas. Caffery had arrived in that room just minutes too late to save him. Most officers who’d worked Operation Norway insisted on keeping the sound turned down if they had to watch the video. Not Caffery. For Caffery the soundtrack was another place to search for answers.

He let it run through to the place where he’d arrived and the hooded man had fled. Then he skipped back to the beginning, to the part he was interested in: the first five minutes when Dundas had spent time alone in the room, strapped to the bench, before the hooded man began the beheading. Caffery pressed the headphones to his ears and shuffled forward in his seat, his face close to the screen.

The name ‘Operation Norway’ was arbitrary. The case had had nothing to do with Norway, the country, and everything to do with Africa. The hooded man – ‘Uncle’, as they called him – had been running a scheme among the African community in Bristol. Through greed, sadism and chance he’d tapped into the community’s ancient belief, called loosely ‘muti’, or African black magic, that some parts of the human body could be used to treat certain medical and spiritual conditions. Over the last ten years there had been just eight cases like this in the whole of Europe and for the British police it was uncharted territory, but what they had learnt was that a human head, the head of a young man, especially one that had been removed when the victim was alive, would fetch a huge amount of money in some circles. That had been Dundas ’s misfortune.