An Admiralty summons to England cuts short Thomas Kydd's service in the turquoise waters of the Caribbean. While the crew of L'Aurore can look forward to liberty and prize money, a shadow hangs over their captain: the impending court martial of his one-time commander, Commodore Popham, who led a doomed attack on South America.

Following Nelson's death two years earlier, England is in desperate need of heroes, and Kydd's Caribbean exploits are the talk of London. Feted by the king and a grateful country, Kydd is soon on detachment in a new and dangerous sphere of interest: the Dardanelles, connecting the Mediterranean Sea to the Black Sea and providing a route to India.

The French have long coveted this route, knowing that it could be the key to toppling the British Empire in India. When they successfully whip up such strong anti-English sentiment that the British ambassador to Constantinople has to flee to L'Aurore, a deadly stand-off ensues.

Meanwhile Kydd's closest friend, Nicholas Renzi, has assumed a new role that he can never make public. Sent under alias on a mission to Constantinople, Renzi must engineer a coup that will turn the tables on the French. But when he's taken prisoner, only Kydd's superb seamanship and sheer bravado can save the day.