Lorna passed them by without a second glance, driving relentlessly forward, her breathing more ragged now, but her feet still pounding the cinders. Further iron fencing appeared on her left. Whatever lay behind that was lost in total darkness. Then, from somewhere not too far behind, there came a sharp cry of pain.

Lorna glanced backward again, once and then twice, the second time looking for longer, trying to focus through the dimness.

The second runner, the woman or girl, appeared to have fallen, and now rolled about on the path alongside the fourth of the garages, both hands gripping her left knee.

Lorna continued forward, determined not to be distracted from her schedule, though already her heart was sinking because almost immediately she’d realised that she was going to have to go back. She was a civilised being, after all; you couldn’t just ignore it when someone had an accident. She tromped on along the towpath for a dozen or so yards, glancing backward again and again, hoping against hope that the diminishing figure would be getting back to its feet. But increasingly difficult though it was to see, it looked as if the woman, whoever she was, was still on the ground.

With no other option, Lorna slowed to a halt, turned and, with shoulders heaving, trudged back along the path.

‘You all right?’ she asked, as she approached the fallen shape.

‘I’m so sorry,’ the girl whimpered, sitting upright on the path but still clutching her knee. In the half-dark, it was difficult to be sure, but she sounded young, no more than a teenager. ‘I don’t know what I’ve done.’

‘What happened?’

‘I don’t know … I’m just glad you came back. I didn’t want to be stuck here on my own.’

‘Let’s have a look.’ Still breathing hard, fresh sweat glinting off her arms and shoulders, Lorna knelt down to make a quick examination. ‘If you can just roll up your—’

The girl stuck her in the bicep with a syringe.

‘Hey!’ Lorna jerked backward. ‘What the hell do you …?’

Instantly, she lost focus, the towpath seeming to tilt, her words slurring. When the girl reached up and grabbed her by the wrists, she resisted as much as she could, struggling as they grappled with each other, trying to roll back onto her heels and push herself away – but suddenly Lorna couldn’t maintain even that minor effort. Within moments, all strength and coordination had left her. She slumped sideways onto the cinders, while the girl got hurriedly to her feet, panting. A deep, sluggish cold now surged the length of the athlete’s body. She was only vaguely aware of the rough ground against her cheek, her blurring vision fixed across the water on the towering brick structure of a mill, which overlooked the scene of her defeat with broken, empty windows.