Australia's spectacular Great Barrier Reef was a graveyard for shipping. HMS Rattlesnake, an ageing British warship, was commissioned in 1846 to survey this magnificent 'Coral Sea' and to produce the first detailed chart of the New Guinea coast. Every reef, every shoal, every rock hazard has to be located and mapped with extreme accuracy. At stake was the pre-eminence of British sea power - and the ambitions of those on board. If all went well Stanley, the ship's brilliant captain, could expect a top job in the Admiralty; MacGillivray, the gifted naturalist, would be the world's expert on the fauna of Australia and the unknown New Guinea; and Thomas Huxley (destined to become the most famous proponent of evolutionary theory after Darwin and grandfather of Aldous Huxley), the ambitious young surgeon, could abandon the dreary routine of the naval service for the excitement of the new world of science. But a series of highly dramatic events and encounters ensures that by the time the Rattlesnake finally returns to England, the glorious dreams of at least some of her crew have met with tragedy...