After a lifetime of abuse at the hands of superstitious townsfolk, Ophelia Young, a bastard child of the notorious pirate queen, is tired of paying for the sins of her mother. Despite playing by the rules her whole life, she's earned nothing but spite and suspicion. So when a naval officer saves her from the jeering crowd at her mother's hanging, Ophelia hatches a new hope of enlisting in the navy to escape her mother's legacy and redeem her own reputation for good. But Ophelia soon discovers that a life at sea isn't as honorable as she hoped.

Betsy Young is as different as she could be from her half-sister Ophelia. She's a nervous homebody who wants to keep her family safe and longs to be in love. So naturally, she's devastated when the son of their family's business partner rejects her hand in marriage and her sister joins the navy. But when her father contracts a life-threatening illness as well, Betsy has to bring Ophelia home to save the family business.

Unfortunately for the Young sisters, Betsy trying to get Ophelia recalled reveals that Ophelia enlisted fraudulently under Betsy's name, a secret which Ophelia struggles to keep from crewmates who would kill her if they knew she was the pirate queen's daughter. To save Ophelia from the naval authorities, Betsy will have to board a ship during hurricane season and brave all the dangers of the sea to get them both home safe.