Marina (Anna Friel) and Holly (Michelle Williams) are two best friends growing up in the London suburbs of the 1970s. As teenagers they experiment with drugs and boys, their close bond seeing them through all kinds of trouble. When they later attend university together, and both begin sleeping with the same professor (Kyle MacLachlan), the relationship enters troubled waters. Will the girls be able to separate and start again? Will they find the courage to step out into the world alone?