Forty-three year old gynecologist David Erneman has just broken up with his mistress of one year, twenty-one year old Susanne Verin, one of his patients who is married herself. David's wife of sixteen years, Marianne Erneman, found out about the affair, letting David know that she knew by walking in on him and Susanne at an out-of-the-way hotel during one of their apparently not-so-secret liaisons. In a tit-for-tat move, Marianne decided to embark on an affair of her own, with her ex-fiancé, sculptor Carl-Adam. Carl-Adam and David were once friends, David who was supposed to be Carl-Adam's best man at Carl-Adam and Marianne's wedding, that is until that morning when David and Marianne professed their love for each other for the first time. Following his split with Susanne, David, upon learning of Marianne's upcoming movements, decides to follow her on the train trip from their home in south central Sweden to Malmo and then to Copenhagen, where she is planning to meet with Carl-Adam. Thinking to his own parents' now fifty year marriage, David knows that that is what he wants with Marianne. But merely following her and telling her his true feelings may not be enough to save their marriage, although David seems fairly certain of the outcome of this literal journey. Carl-Adam, with a little help from a seductive friend named Lise, may have some say in the matter.