"Sophie was desperate to feel rapture once more. She'd do anything to experience it again. Having sampled it, she knew she couldn't go on without savouring it time after time.

Already, she was addicted to it. Elation was becoming her reason for living. She used to think that running was everything but now she knew that, if some terrible accident ruined her legs, she'd be able to carry on without the thrill of racing. "Is there a high beyond the winning of races? Even on the way to becoming an Olympic runner, Sophie thinks so.

But what Sophie thinks is not normal because her brain has been altered.

She's had an experimental medical treatment to help her cope with a massive childhood trauma.

Now, the sight of blood brings out very different feelings in her.

Is this unexpected side-effect making her dangerous?

Her new running partner, Jonah, looks set to find out. Sophie's always chasing. Chasing the championships. Chasing another personal best. Beyond the finish line, she's chasing the rapture.