Mirabel is a girl stuffed into society. She would rather sail the open waters with her best friend, Cai. What she doesn't expect is a whole adventure. When Mirabel leaves her home with her best friend, Cai, to sail the seas, they stumble across something they never thought they would. A selkie boy. He decides to help them for reasons unknown. Mirabel's father chases them across the ocean when she leaves. Along the way, her crew encounters the island of gold, a mystical being, and a pirate crew of all girls. Her father pursues them until the end. What will happen?