Fiona Maye (Emma Thompson) is an eminent High Court judge in London presiding with wisdom and compassion over ethically complex cases of family law. But she has paid a heavy personal price for her workload, and her marriage to American professor Jack (Stanley Tucci) is at breaking-point. In this moment of personal crisis, Fiona is asked to rule on the case of Adam (Fionn Whitehead), a brilliant boy who is refusing the blood transfusion which will save his life. Adam is three months from his 18th birthday and still legally a child. Should Fiona force him to live? Fiona visits Adam in hospital and their meeting has a profound emotional impact on them both, stirring strong new emotions in the boy and long-buried feelings in her.