In 1973, Maurice receives an invitation to come and visit his old friend Victor, a former trade union leader, at home. When he arrives, Victor's wife Sonia greets Maurice with hostility. Victor pretends to her that Maurice is only visiting by chance. After she leaves, Victor tells Maurice of a book he is writing on the history of art. He also admits that he is dying of myeloid leukaemia and only has a few months left to live. He hasn't told Sonia. He shows Maurice a letter that Sonia has mailed to him and then brought to him with the rest of the post. Maurice reads the letter, which recalls her and Victor's courtship and how they first clashed over her conventional religious upbringing.
Victor phones Maurice and asks him to come round to the house with his comments on his manuscript. He is concerned that he has begun to write the book too late. Maurice leaves for a two-week trip to America. He reads Sonia's second letter, in which she remembers how she shocked him by refusing to feel sorry for him during a bad patch with the unions, as he was so self-pitying already.
Maurice returns from America and goes to see Victor. Sonia is still sullen and unwilling to talk to him. He has tea with Victor in the garden. Victor and Sonia have argued, as she wants to go the Moors where they first courted, but he feels too weak, though he still hasn't told her that he is dying. Victor is bitter and angry and admits his fear of his imminent end. He criticises himself for wondering if there is an afterlife, as he has always been an atheist. Maurice gives him a sketch that may be by John Ruskin, which cheers Victor up greatly. While Victor changes out of his pyjamas to meet some of his old colleagues, Maurice comes across an unfinished letter that Sonia has left on the writing desk. She passionately describes the landmark of their early life together and Maurice is embarrassed when Sonia describes their sex life. Maurice and Sonia are both shocked at how badly Victor fits into his old suit. They share a glance and Maurice sees that this shared moment is of great significance. After speaking to his old friends, Victor is exhausted and Maurice puts him to bed. On his way out, Sonia kisses him.
Victor is angry that his eyesight is starting to fail. When two letters from Sonia arrive on the same day, he and Maurice sit and read one each. She describes their wedding day and the birth of their son and a trip in which they went climbing with their two children. Victor remembers that she hated his working for the trade union and that for a long time things were very bad between them, though during the same period Sonia grew in confidence as a person. While Maurice drives away, he realises, with some shame, that he is glad that he is not the one who is ill.
Victor is in hospital and railing at the unfairness of his predicament. Sonia's latest letters tells of the great pride she feels in how Victor helped shape her and the children into the people that they were truly meant to be. She tells him of how proud she is to be his wife and the mother of his children.
Victor is increasingly worn down by the hospital treatment. He is now resigned to his death and to the fact it awaits everyone, even the members of his family. Sonia's new letter describes her intense and passionate love for Victor. As Sonia cleans Victor's now empty room at home, she bursts into tears.
Maurice arrives at the hospital half an hour after Victor's death. Victor leaves behind the manuscript and Sonia's letters. Maurice and Sonia kiss and embrace as she leaves the hospital with her family. Maurice reads her last letter, where she tells Victor, "In the instant they know death so they know truth. In the blinding light of truth they know death, one and the same. Trust me, love, oh my love, oh my Victor, oh my heart".
