The stars are being eaten by a living darkness—a demigod of nihilism named , the Forgotten Son. Long ago, Nukutū was the first wayfinder, but when his entire fleet drowned due to his pride, he cursed the ocean itself, vowing to erase every journey, every memory of exploration, until the sea is a black mirror of his own grief.

They reach the Horizon’s End—a literal cliff where the ocean falls into starlight. Nukutū isn’t a monster; he’s a hollow, whispering figure in a broken canoe. He offers Moana a deal: Give him one memory of home—her sister’s laughter, the smell of baked breadfruit, her grandmother’s voice—and he will stop the Undoing Tide.

Moana discovers a hidden chamber beneath Motunui’s sacred mountain. Inside is a thousand-year-old lali (drum) and a star compass pointing to a blank spot on every map. The ancestors carved a warning: “Beyond the known sea lies the Horizon’s End. No voyager returns, lest they bring the sky back home.”

Motunui hosts the first Great Voyaging Festival in centuries. Moana restores the lali drum, and for the first time, she teaches Simea how to read the stars. The final shot is Moana, Maui, and the crew sailing not away from home, but toward a chain of undiscovered islands—not as explorers, but as relatives.

But something is wrong. Navigation stars are vanishing from the night sky one by one. A patch of the ocean near Motunui has turned dead, glassy, and silent—no fish, no wind, no waves. Moana’s grandmother’s spirit appears in a flicker of bioluminescence, whispering a name Moana has never heard: “Lalotai’s Shadow—the Undoing Tide.”

Three years after restoring the heart of Te Fiti, Moana must answer a mysterious call from her ancestors and lead a new crew of unlikely voyagers across the most dangerous ocean on Earth—the forgotten realm of the Hidden Horizon—to break a curse that is slowly erasing the islands of Polynesia from existence.