Newly-promoted Captain Nathan Peake has been dispatched to the Caribbean to take command of the British navy's latest frigate, the 32-gun Unicorn, a ship with an already tragic history of mutiny and murder. While Peake settles in, the Revolutionary authorities in Paris send out the Virginie—the best 44-gun warship in the French fleet—on a secret mission to spread war, rebellion, and mayhem from the shores of Cuba to the swamps of the Mississippi Delta. While the Unicorn embarks on her epic duel with the Virginie, Peake confronts the seductive charms of Sabine Delatour, the witch-queen of the Army of Lucumi; the intrigues of the American agent Gilbert Imlay; and a lethal combination of Barbary pirates and Irish rebels.