The father got up and cast him a baleful look. “Don’t bring bad people here.”

“Since I’ve been called a bad man once already this morning, I’ll have to count myself among their number.”

Father John stalked off to the vestry to collect Petrovitch’s bag. Sister Madeleine leaned down and waited until the father was out of sight. “Come with me,” she whispered.

“I’m just going to get you into more trouble, and none of it the interesting kind.”

“I can look after myself. Just come.” She walked to a side door, turned the heavy key and pulled the bolts aside. Stale air blew in as she worked the latch. Petrovitch dragged himself out of the pew and followed.

There were stairs, going up in a tight spiral, which she had difficulty negotiating because of the width of each step and the height of the ceiling, and he had problems with because he grew rapidly breathless as he ascended.

She opened another door, a trap door which she unbolted and threw back. Light poured in, making them both blink. She led the way onto the roof of the tower, and turned a full circle, taking in the view.

It wasn’t much. Immediately to the north was a raised section of dual carriageway, crammed with traffic. South and east were the cramped streets of old London, the skyline filled with the skeletons of cranes and new buildings, each trying to outdo the last for height. To the west was the rising ground of Notting Hill, where the wealthier post-Armageddon refugees had squatted.

Petrovitch leaned heavily on the parapet and wiped his damp forehead with the back of his hand. “I can’t believe you’ve got me all the way up here just for this.”

“Look,” she said, pointing beyond the flyover. “See those buildings? That’s the Paradise housing complex. It used to be St. John’s Wood, before they bulldozed half of it.”

“Yeah,” said Petrovitch. There were seven tower blocks, ugly, utilitarian shapes, their bases hidden in a yellow haze. The concrete looked scarred and cracked. “Doesn’t look like they deserve the new name.”

“They call themselves the Paradise militia,” she said, and leaned on an adjacent piece of brickwork, staring out over the city with faraway eyes. “They run the blocks, and everybody in them. It’s like a city-within-a-city, with an economy based on crime. That’s who Father O’Donnell took on.”

“So they killed him. Shame, but I don’t know why you’re telling me this.”

“I want you to understand.” She tilted her head to face him, brushing the side of her veil away where it obscured her view of him. “Father John…”