Father Keith (Guy Pearce), mother Megan (Amy Ryan) and 17-year-old daughter Lauren (Mackenzie Davis), live a comfortable life but there is something missing. Megan is never quite satisfied with the ways things are. Keith has given up his dreams of being a musician for the steady paycheck of a music teacher. When a beautiful foreign exchange student, Sophie (Felicity Jones), comes into their lives, Keith is soon drawn to her.
She's mature beyond her years, and yearns for someone to make her feel safe and loved. Their feelings build for each other, they share deep looks, and the occasional touching of hands, which only increases the intensity of their bond. When they finally decide to run away together, they set into motion a series of events that lead to an almost inevitable tragic conclusion.