In the enchanting depths of a mysterious cave on Sardinia, Tottoi's world transforms when he encounters a rare and endangered seal species. Entranced by the beauty of nature, Tottoi explores the island's beaches and caves, leading him to a heartwarming discovery of a seal cub and its majestic mother. As a bond forms between them, Tottoi's joy turns to anguish when adults threaten to disrupt their peaceful existence by capturing them for display. Faced with a difficult choice, Tottoi must protect his newfound friends and ensure their freedom, even at the cost of his own attachment.