London, 1929. Eleanor Hamilton is a dutiful mother and adoring wife to a celebrated war hero. Her husband, Edward, is a leading light in the Eugenics movement. When their young daughter, Mabel begins to develop epilepsy they face a moral dilemma as she is one of the undesirables Edward campaigns against. Forced to hide the truth so as not to jeopardise Edward's life work, the couple must confront their past, and the secrets that have been buried.