A group of Dutch tourists strolled past him and a slightly intoxicated straggler smiled and said something in English. De Payns smiled back and answered in French. The Dutchman went straight into perfect French, telling de Payns about the bars they’d just visited and the seafood restaurant they were heading for. They made small talk, de Payns walking on the building side of the footpath, giving him a view of the approaching traffic. No Mercedes, no tall Turkish thug.

The group closed on the crossroads of Roma and Cavour, and de Payns turned left onto a four-lane, leafy boulevard with two-hundred-year-old buildings on each side. The older ones didn’t exceed four storeys, while some of the newer apartment buildings were higher. American jazz floated from an old apartment above him while Algerian rap bellowed from a passing car. Via Roma was bathed in a golden glow, the last embers of the Mediterranean sunset illuminating the street. Ahead he saw a silver Mercedes 4x4 flashing across the street, but it didn’t slow. There were thousands of silver SUVs driving around Europe in the dusk, de Payns reminded himself; it could have belonged to anyone.

He walked north for twenty minutes and ducked into one of Old Palermo’s medieval lanes, which became narrower and more winding as he progressed. Vespas and Japanese scooters were parked against ancient apartment walls, and he pricked his ears for the echo of footsteps behind him, but all he could hear was the blaring of a television and women raising their voices.

At the end of the lane was a small square with a narrow church fronting it. He’d discovered this place during a walk he’d taken six weeks earlier, when familiarising himself with the city and looking for a good place to do an IS. It was perfect for what he wanted—the front door was ajar and he walked into a candlelit church. A priest in short sleeves spoke with two elderly women off to his right, and de Payns kept walking along the left of the pews, through a side door and down the corridor to another door. He opened it and looked out to a street on the next block. Many old churches in European cities covered one block, but they’d been built around over the centuries. Once you’d passed through and were out the other side, you could disappear into the surrounding streets while the followers in vehicles had to go the long way around the block. If walking followers really wanted to stick with you, they were walking through a point de passage obligé—a choke point they had to move through—and were hence declaring themselves.