To escape a sea god's curse that will turn him into foam unless he loves a human, the proud merman-witch Seth is forced aboard Captain Arthur's pirate ship. Trying to complete his task, Seth attempts to use magic to force love, but unexpectedly reunites with his childhood friend, the now cold and powerful Captain Arthur. Arthur, cherishing their childhood token, loyally protects Seth, while the amnesiac Seth wavers between manipulation and true feelings. As the false "bride" Leo appears and the schemes of their childhood bully Eddie surface, the two navigate trust, betrayal, and sacrifice to confirm their feelings. Ultimately, Seth regains his memories and power, and the couple sets sail into the horizon, bound by love and witnessed by all.
