James Nesbitt plays radiographer Joe Keyes. Late one night he is travelling home by train when he sees a young girl, Alice (Emily Bruni) being chatted up by two men. When the banter becomes threatening Joe is unsure whether or not to intervene. When he reaches his station he glances at Alice who seems to be appealing for his help. Now he faces a dilemma. Should he stay on the train and get involved or get off and go home? Joe chooses home. His actions result in terrible consequences for Alice, his wife Helen (Siobhan Finneran) and his two children - but most of all for his sense of identity. Writer Tony Marchant says; "A man makes a fateful decision that systematically takes apart his authority as a husband, a father and a man. It's ultimately about how hard it is to be good and do the right thing.