Five months after the end of the Civil War, Acting Navy Lieutenant Everett Townsend is awaiting discharge in Key West. The end of the war has left him uncertain about his future and full of regret about the end of his relationship with Emma, the Cuban American daughter of a Havana boarding house owner. His Spanish grandmother- a slave owner who runs a prosperous sugar plantation in the Cuban countryside- is dreaming that Everett will return and take over the family business, a prospect that sickens him.

Returning from a routine supply mission from Fort Jefferson in the Dry Tortugas, he and his men are caught in a hurricane and witness a shipwreck in the Marquesas Keys. When they investigate, they discover a locked cargo hold with the dead bodies of Black freedmen. When Townsend reports this unsettling incident to his distracted Naval commander in Key West, he's encouraged to drop the matter. But he can't shake his suspicions that the poor souls from the cargo hold were destined for re-enslavement in the sugar fields of Spanish Cuba.

The murder of an American sailor in a Cuban port provides Townsend with a reason to return to Cuba and continue his investigation even as it reunites him with Emma who has joined the secretive Cuban resistance to Spanish colonial rule. A rescue of a Navy veteran leads to more clues and helps convince Townsend to become a government informant operating in the interior of Cuba. He goes to live with his Spanish grandmother at her sugar plantation in the Cuban countryside. There Townsend finds himself facing an impossible choice between the Cuban-American woman he loves and his tradition-bound Spanish grandmother. As he grapples with this clash of personalities, Townsend uncovers the details of a conspiracy which forces him to come face to face with his own family's close ties to slavery.