Springboards from the Hans Christian Anderson fairy-tale of "Den lille Havfrue" ("The Little Mermaid.")

Adva sacrificed herself in hopes of giving Prince Peter happiness. She is turned into sea foam and drifts at sea, barely remembering who she is, though still deeply in love with Peter.

Now human again, Adva learns that the Peter has lost his mind in the wake of her apparent suicide, and his younger brother, Stefan, plots to take over the kingdom in his place. Determined to save the man she left everything behind for, she decides to infiltrate the castle to free him, but even when aided by true love, matters are never that easy.