Story of an innocent and carefree little girl whose father is a member of the anti-French resistance.

The inhabitants of a small island in the delta of the turbulent Red River are doomed to poverty: floods wash away crops, livestock, and even people. From generation to generation, a legend is passed down about a kind dragon that can drink the river's water and save the village. But the dragon is a fairy tale, and the people have decided to block the treacherous river themselves. With extraordinary perseverance, fighting against the elements, the village population builds protective fortifications around the island.

Rapid rising water in the river can potentially break the dike and cause disastrous flood endangering the villagers. Miss Dung, Chairman of the Commune, must find a way to persuade people to destroy the minor dike and sacrifice some parts of their houses and land in order to protect the main dike.