Married to Maggie with two teen-age children Carl Matthews is disenchanted with his job at a commercial lettings agency to which he commutes daily. Fellow commuter Sally Thorn, who manages a gym, is divorced but engaged to Ryan, who annoys her with his insistence on a lavish wedding. After fighting over a seat on the train Sally and Carl become friends and the friendship turns into an affair. Carl, now made redundant, hopes it will never end but Sally is more realistic, particularly as she is pregnant by Ryan, who wants them to move to Australia. Learning of the affair Maggie throws Carl out but both she and Sally turn up at Casualty after Ryan has beaten Carl up. With which of the women will Carl eventually end up?