When Spain joined the Seven Years War on the side of France, one of its aims was to conquer Britain’s ally, Portugal. They launched three separate land invasions, each of them ultimately unsuccessful, but each a deadly, existential threat to their neighbour. Portugal, meanwhile, was determined to hit back at Spain’s sprawling colonial empire, and the Debatable Lands between Brazil and the River Plate Estuary offered a tempting target. Finding themselves short of ships, the Portuguese government contracted a London company of merchant adventurers to provide two large privateers as the naval element of the expedition.

In September 1762 George Holbrooke, in his frigate Argonaut, is sent on a six-thousand-mile voyage to assist the Anglo-Portuguese expedition. However, Argonaut is not the only man-of-war heading for the River Plate. He finds a familiar adversary already there, eager to settle old scores. The scene is set for a final battle and the winner will be the captain who can best exploit the shifting sandbanks of this shallow estuary. This sixteenth novel concludes the Seven Years War series. The Carlisle and Holbrooke naval adventures will continue as Britain and her American colonies set out on diverging paths with different visions of the future.