Interweaves two stories: John Harrison's forty-year obsession with building his perfect timekeeper, known today as the chronometer; and naval officer Rupert Gould who, two hundred years later, stumbles across Harrison's forgotten chronometers and devotes himself to restoring Harrison's long-neglected mechanical masterpieces.

Anyone alive in the eighteenth century would have known that "the longitude problem" was the thorniest scientific dilemma of the day -- and had been for centuries. Lacking the ability to measure their longitude, sailors throughout the great ages of exploration had been literally lost at sea as soon as they lost sight of land. Thousands of lives, and the increasing fortunes of nations, hung on a resolution. The quest for a solution had occupied scientists for the better part of two centuries when, in 1714, England's parliament upped the ante by offering a king's ransom (£20,000, or approximately $12 million in today's currency) to anyone whose method or device proved successful and reproducible. The scientific establishment throughout Europe -- from Galileo to Sir Isaac Newton -- had mapped the heavens in it pursuit of a celestial answer. In stark contrast, one man, John Harrison, dared to imagine a mechanical solution -- a clock that would keep precise time at sea, something no clock had ever been able to do on land" --Cover, p. 2.