In a small and picturesque Irish village, a boy named Ben lives with his family in a lighthouse by the sea. His life takes a tragic turn when his mother disappears into the ocean, leaving him with his distant and gruff father. One day, while exploring nature, Ben discovers his younger sister, Saoirse, an enigmatic girl who is the last of the selkies, magical creatures that can transform from seal to human.
Saoirse lives with a seal coat that allows her to swim in the depths of the sea. However, she has never spoken, due to a spell that keeps her silent. When a mysterious spirit draws her towards the water, Ben embarks on a mission to help her find her voice and free the magical beings of Irish folklore that have fallen into oblivion. As the story unfolds, the siblings traverse breathtaking landscapes and face fierce adversaries, such as a witch who tries to keep Saoirse in the human world.
With the help of a family of magical animals, and confronting their own fears and insecurities, Ben will learn about the importance of family connection and sacrifice. Among the captivating music and stunning animation, this magical adventure is a celebration of Irish culture and a reminder that the bonds of love can guide us even through the darkest storms.