The Black Swan (Historical Novel). Rafael Sabatini

Priscilla Harradine is the daughter of the recently deceased governor of the Leeward Islands in the West Indies who travels back to England with her father's second-in-command, Major Bartholomew Sands. Sands plans to marry Priscilla upon returning and to live in comfort off of her inheritance. However, a late passenger boards their ship and it turns out to be an ex pirate Charles de Bernis, mysterious and rogue character who obtains Priscilla's attention. As their friendship grows, a shady person from buccaneer's past comes back to haunt him and takes them in a dangerous adventure.