Young Hana lives alone in a dilapidated villa on the riverbank. She is plagued by fears, takes antidepressants, and avoids people who, in turn, reject her. Only Jarda is different; he is hopelessly in love with the delicate, fairy-like woman who seems so strange and unreachable. Wanting to help her, he invites her former psychotherapist to visit and try to reach Hana. But the well-intentioned attempt fails completely—Hana drives the doctor out of the house.

A secret surrounds Hana, who is mysteriously drawn to water. As a child, she played with tadpoles in a tin tub and even swallowed one. Now, she is visited at night by a creature that rises from the garden well—her father, a water spirit. Her mother was in love with him, and Hana was conceived in a pond.

Only when Hana jumps from the bridge into the river and seemingly drowns is she reborn—as the being she was always meant to be: half human, half fish. Only then does she find inner peace and mental health.

But in the town, where everyone is busy with their own lives and daily worries, she remains a stranger. A jealous rival who wants Jarda for herself even tries to kill Hana.

It rains, the river rises, and Jarda launches a homemade boat—his gift to Hana. She accepts the invitation to board the boat, embraces Jarda, and is finally able to show him her love. Together, they explore the mysteries of the water.

Days pass, the rain continues, the river swells and overflows its banks, washing ashore all the trash carelessly thrown in by people. Hana, the water creature, expands, transforms into the river itself—she becomes the flood that inundates the town.

After the flood, the townspeople manage to rebuild their homes; Hana and Jarda also restore the heavily damaged villa by the river.