1786: Captain William Rennie is on the beach and on half pay. Things weren't always so bad for him. Four years earlier Admiral Rodney had singled him out for his part in the glorious Battle of the Saints, but since then he has found himself ignored by the Admiralty, and his career has all but gone by the board. With so many officers in the same position in the peace, with most of them having greater hope of preferment, Rennie is amazed when he's given a prime commission: HMS Expedient is a 36 gun frigate; she is to be sent to the South Seas on a scientific expedition. For Lieutenant James Hayter, in Dorsetshire, whose career had barely begun when the peace came, his own commission in Expedient out of the blue is equally surprising and exciting. Leaving his home and his sweetheart for at least a year is a small price to pay for this heaven sent opportunity to get to sea again. But for these two sea officers there is something odd and disturbing about the nature of their task. They sense that they are not being told the whole truth about the forthcoming expedition, and the shady, powerful figure of Sir Robert Greer is always at their backs. There is trouble at the dockyards - delays and disputes - and vexing difficulty over scientific instruments. There are clashes of personality, and unwelcome additions to the ship's complement just as she is about to leave harbour. Then a long series of mysterious accidents and setbacks as Expedient sails south. Is someone trying to sabotage their mission? Why is their progress dogged by a mysterious man of war? And what are the secret orders locked in Rennie's cabin which may only be opened once they round the Cape of Good Horn? The answers lies on a beautiful uncharted island, in the remotest corner of the Pacific immensity, to which the storm-battered Expedient limps for desperately needed repairs. Soon the dangers of the voyage will pale in comparison with what they discover there, across the limpid waters of the lagoon...