It had its world premiere on 23 February 2020 at the 70th Berlin International Film Festival,[4][5] where it was selected to compete for the Golden Bear in the competition section.

[2] Undine Wibeau, a historian who lectures on the urban development of Berlin, is broken up with by a married man with whom she is having an affair, Johannes.

Christoph is fixing a turbine in the Lingese when he sees a giant Wels catfish that he and his colleagues affectionally refer to as Big Gunther.

After Christoph leaves, Johannes asks to meet with Undine, telling her he has made a mistake and should not have ended their relationship, but she rejects him.

Arriving at the Lingese, she discovers that an accident left Christoph trapped underwater without air for 12 minutes and he has been hospitalized in a braindead state.

After Nora heads inside, Undine enters the pool with Johannes and drowns him, before submerging herself in a body of water.

The website's critical consensus reads, "Undine draws on folklore for a dark fantasy whose murky storytelling is often offset by the enchanting romance at its core.