It's the summer holidays - and there's a strange boy at the bottom of Flynn's garden. Soon, she and her wayward brother Sam are walking out of the house in the middle of a hot summer's night and crossing four fields to find him again. But as well as the boy, Flynn and Sam find a whole gang of runaway kids. There's Diana, who's just had a baby. There's Mouse, who's only six and likes to set fire to things. And there is the boy himself, who stirs up feelings in Flynn that she's never felt before. But there's also someone else - the unspeakably malign and terrifying presence they're all running from . . .