While stationed abroad during World War II Henry Tillotson has married a complete stranger at his father's request. When the war is over, and his father has died, Henry brings his bride with him back to his estate, Cotteshaw, in the West Country. The first thing the bride does on their arrival is to give her husband a black eye and without a word march upstairs to her bedroom where she will reside for the best part of the rest of her life. Two young couples, Antonia and Matthew, and Barbara and James, begin to visit Cotteshaw frequently. Unwilling to admit it, the two young ladies are attracted to the fifteen years older Henry Tillotson, and fascinated and frightened by his mysterious wife, Margaret, who will endure their visits in her bedroom with bored superiority. Margaret Tillotson is beautiful - but mad. She likes to make up malicious stories about everyone at Cotteshaw and enjoys inflicting pain on everyone who comes into range, preferably without lifting her head from the pillow. Her husband reacts to her fancies with indulgence and nauseating kindness while he tries to be a host to his guests. The nature of his wife means that Henry Tillotson is in need of an heir, and Margaret refuses to divorce him. However, the two couples keep returning to Cotteshaw throughout the years, and every time Henry is the perfect and attentive host, especially to Antonia and Barbara.