Still haunted by the disappearance and death of the girl he loved as a teen, university professor Sam (Guy Pearce) meets a woman, Ruby (Helena Bonham Carter), on a train, and they hit it off. But Ruby disappears when Sam is distracted. Later that same night, he spots her falling from a bridge into a lake. He rescues her, but Ruby doesn't remember who she is. Slowly, she starts to feel oddly comfortable with Sam, and he begins to believe that she may be the reincarnation of his dead love.