 When the British Parliament creates an award of £20,000 to whoever can come up with a solution for determining longitude at sea, a carpenter-turned-clockmaker, John Harrison, begins his experiments to build an accurate timepiece unaffected by sea travel. His main obstacles are lack of money, a judgment Board convinced that the answer lies in astronomy and not clocks, and the mechanics of the clock itself. Rupert Gould, a retired naval officer who suffered a nervous breakdown in WWI, has been researching Harrison s history and makes efforts to locate and restore Harrison s clocks. Harrison s and Gould s struggles are linked by the clocks which the two men will, across 200 years, make tick accurately enough to measure longitude.