The Runaways — Ruth Thomas

Julia and Nathan have no friends to speak of. They're misfits of Mrs Henrey's class - awlays the last to be picekd for the team, and always without a partner. Then they discover a stash of money in a deserted house and suddenly, instant popularity seems just around the corner. But so is trouble, in the shape of the adults who start asking difficult questions. There is only one thing the pair can do now, and that is to run away!