An epic adaptation of Dava Sobel's best-selling book, starring Michael Gambon and Jeremy Irons. Longitude is the fascinating story of John Harrison (Gambon), who in the 18th century believed he could make a clock that would work on board a ship - and so solve the problem of finding longitude at sea. Harrison has to struggle against a bigoted establishment in order to win recognition for his achievements. This story is intertwined with that of Rupert Gold (Irons), the former naval officer who in the 1920s discovered Harrison's clocks and - at the cost of his health, his reputation and his marriage, began the mammoth task of restoring them.