Marrying the Dragon Tyrant in Place of Her Sister

To save her sister from a death foretold by a magic mirror, Mermaid Princess Mabel takes her place as a bride in Stormspire. Her groom is the handsome Lieutenant Adrian, secretly the feared Dragon Prince. Bullied and targeted by jealous Lydia, Mabel fights back, wins her husband's heart, and founds the Tideway shipping guild. But when both spouses' secrets surface, can their love survive the truth?