Lucy slammed her visor shut and screeched down the other side of the rubble on her rear wheel. Masonry and grit showered behind her as she raced across the cellar, skidding to a halt alongside the ex-nun, who was looking up again, and indicated with a limp, bloodstained hand that she was okay.

Lucy sped on, passing through the narrow doorway and entering a long, concrete passage that had never been intended for vehicles. Again, it was cluttered with debris, as though part of the ceiling had collapsed, which made it difficult going. A dark shape bobbing ahead of her revealed her fleeing prey, but before she could catch up with it, she reached a junction of passages obstructed by a wheeled cart that was loaded with wooden pallets.

Lucy braked sharply. She heard feet hammering away ahead as she leaped from her seat to shove it all aside. What this place had once been, she couldn’t fathom. Whatever it was, if the rest of the structure was anything to go by, it was likely to be labyrinthine, which was all she needed when her quarry had a head-start like this.

She clambered back onto her bike and accelerated forward at reckless speed. At the next intersection of corridors, she had to slow down to listen. Hearing an echoing clatter of rubble on her right, she swung her machine after it, accelerating again. It was the same at the next junction. Even with her headlamp on full beam, she now saw nothing but endless concrete tunnels telescoping ahead, black elongated nightmares along which her Ducati hopped and skipped as it cleared mound after mound of masonry. Some were so narrow that at times her handlebars all but carved their way along the walls and turned the reverberation of her engine into a barrage of gunfire; it was thunderous even to Lucy, whose ears were padded by the helmet. Though it probably explained why the fugitive, who suddenly came into view some sixty yards ahead, streaked forward with athletic prowess, no doubt galvanised by the racket behind her, and gained ground with every corner she turned because they were too tight for the bike to take quickly.