Neryssa, a siren in Neverland's hidden lagoon, desires understanding, not fear, unlike her kin. Her solitary existence is disrupted when Peter Pan, immune to her song, discovers her. Their unlikely friendship blossoms as they explore each other's worlds, Peter introducing Neryssa to Neverland's wonders above the sea and Neryssa sharing the secrets of the underwater realm. Their bond deepens, but faces challenges: the Lost Boys distrust Neryssa, jealous mermaids plot against her, and Captain Hook seeks to exploit her powers to capture Peter. A growing darkness threatens Neverland, both above and below the sea, forcing Peter and Neryssa to embark on a perilous adventure to save it. They confront cultural clashes, trust issues, and external threats, learning to compromise and trust one another.

Their journey tests their love and loyalty, forcing them to confront their differences and the prejudices against Neryssa. Through trials, they unravel the mystery behind the shadow threatening Neverland, discovering that their love can bridge the worlds above and below. They ultimately prove that harmony can be found in their differences and that their love, rather than changing them, strengthens them and unites Neverland.