When David (Benedict Cumberbatch
), a schoolteacher, lands a job in his home village of Kent, he and his wife Dawn (Claire Foy
), who's also a teacher, move back.
They live there happily until David's emotionally unstable younger brother, Nick (Shaun Evans), shows up. He's been away in the army and begins telling Claire all kinds of secrets about the village and the people who live there, including secrets abotu his brother, which makes Dawn increasingly uneasy.