A Heritage and Its History tells the story of 69-year-old Sir Edwin Challoner and his extended family. Unmarried, and with no direct issue, Challoner's closest relation, and business associate, is his younger brother, Hamish. When Hamish dies of a heart condition, his son Simon prepares to take over as head of the house, as everyone assumes that Sir Edwin will also die in a matter of months. However, Sir Edwin surprises everyone by announcing his marriage to Rhoda, his neighbour, also more than 40 years his junior.
Following the return from their honeymoon, Rhoda succumbs to a moment of unbridled passion with Simon, her new husband's nephew. When Rhoda falls pregnant, there is no question who has fathered the child. A Heritage and its History gets right to the heart of this family as it splits into factions, growing increasingly bitter and resentful.