After trading her life on land for one on the sea with Ryan and his family, Luna must adapt to a world of uncertainty among pirates. Luna attempts to gather the pieces of her life that her lost mermaid mother left throughout the sea but soon discovers her life as a mermaid princess isn't the only secret of her existence. A life-altering discovery pushes Luna to embrace the pirate life to protect the ocean and influence them to change their brutal ways. But when her need to save a group of innocent boaters puts Luna under the pirate king's scrutiny, she learns that it'll take more than her knowledge of the sea to transform the dangerous surface. If she can't, she and Ryan might never find the life they imagined. And worse, she faces losing everything she loves to the treacherous waves.