In September 1937 Andras, a young Hungarian student, leaves his family and heads for Paris on a scholarship to study architecture. Before he sets off he is given a mysterious letter to post on arrival in Paris. It is addressed to an Hungarian woman and no reason is given why it cannot be posted from Budapest. When Andras arrives in Paris he becomes vitally aware of his poverty, particularly when he enters the home of a richer Hungarian emigre Klara Morgenstern. She is a young widowed woman, and he finds himself falling in love with her. As they begin to meet regularly it is clear that Klara is hiding a terrifying secret, related to the mysterious letter that Andras posted on arrival, which means she is trapped in Paris as war looms closer. And, as Andras and his fellow students lives become ever more vulnerable in the shadow of war, the group must shatter in order to survive. Andras is forced home to a labour camp, his brother disappears and Klara risks everything to return to Hungary to be close to her lover.