Inge (Ursula Werner) has been married to Werner (Horst Rehberg) for 30 years. This elderly couple live in a small apartment in East Berlin; both are retired although at 67 she still works as a seamstress. He is a quiet man who smokes a lot of cigarettes and has a favorite pastime of listening to recordings of trains; for a break from the routine, they go on a train ride through the countryside. He has helped her raise her children from a previous relationship.

One of Inge's customers is Karl (Horst Westphal), a 76-year-old who seems to be a much younger man than her husband. While delivering his mended trousers to him, she looks into his eyes and knows that she is in the throes of a passion that is beyond denial. He evidently feels the same way, and they strip and make love. Feeling guilty about her transgression, Inge does not respond to Karl's invitation to see each other again. Her reason tells her that it was nothing more than a brief fling; her conscience tells her that it was a terrible thing to betray Werner, especially since they still have an active sex life. When she tells her daughter about what has happened, she is told to continue the affair in secret and by all means not to tell her husband.

Inge's body urges her to return to Karl, and they begin a passionate love affair which includes a bike ride to a lake where they go skinny-dipping, run together in the rain, and linger over each other's flesh with tender caresses. He makes Inge feel young again and fuels her dreams of a different kind of life than the predictable and boring one she has with Werner. Karl is a handsome fellow who sees himself as a nonconformist and free spirit. But despite the genuine happiness that rises up in her, Inga decides to confess to her husband, and his response is one that she does not expect.

Andreas Dresen directs Cloud 9 with a playfulness that comes across in the fluidity of the action. It is very rare to see elderly actors doing sex scenes and frontal nudity on screen. But the director has accomplished this feat with a naturalness that is commendable. Ursula Werner won the German Film Award for Best Actress (Germany's equivalent of the Academy Award) for her astonishing and emotionally rich performance. She manages to convey to us all the pent-up excitement and anxiety involved in a love affair that is genuine and complicated.