Berlin. A young historian and diver falls in love with Undine — a city guide with a mythical name who knows everything about East and West Berlin’s architecture. She lectures on urban planning, drinks coffee, wears a white shirt. Everything comes together as if by magic — but Undine has a secret: if her lover betrays her, she must kill him and return to the water. Petzold takes an ancient legend and places it in a familiar, realistic world, turning fantasy into the everyday, and soaking the everyday in quiet enchantment.