Matthew's American cousin comes to live with them: Sam's small, blond and wild – with a giant attitude problem. He immediately starts to wreak havoc on Matthew's social life – getting into fights with his friends and causing a scene whenever they go out.
School is about to start and Matthew and his friends don't want these problems to continue, so they come up with a plan for Sam to prove his loyalty to their gang and to trick the mean girls at school. They dare Sam to go to school for the first week as a girl.
Told from the viewpoint of each of the characters – some funny, some conceited, some achingly sad.