Magic Trilogy #2: Calypso Magic by Catherine Coulter

While visiting London, a beautiful young woman becomes homesick for the West Indies. Unfortunately, her only available chaperone for the perilous journey is her rakish, hot-tempered cousin, the sixth Earl of Saint-Leven. Her destiny becomes one with his as they brave the war-torn seas on a voyage that would take them from regal London to the tropical shores of the Calypso Island. And as the fires of battle engulf the world around them, their desire for one another starts to burn.