Mona (Natalie Press) has just got hold of a brilliant moped that only cost a tenner. No engine but still dirt-cheap. She lives with her brother, Phil, (Paddy Considine) who used to run a pub before he found God and poured away all the booze. Tamsin (Emily Blunt) is rich, spoilt and trying to live a life of seductive decadence.
They meet on the moors, above their quiet Yorkshire village and begin an intense, unlikely friendship. Tamsin is tragic and fantastical, Mona, rough and witty. Tamsin is charmed and Mona is hooked.
Tamsin and Mona want to escape their lives but Phil wants to save them and save everybody else. Mona wants the old, dangerous, Phil back; the brother that she loved. Tamsin wants to see what it takes to break him.