The story begins in Milan. Lidia is married to Giovanni, a famous writer. After visiting the clinic where their longtime friend Tommaso is seriously ill, they attend a party for the launch of Giovanni's new book. The crisis in this couple's relationship is analysed through the events from morning until night. Lidia leaves the party, bored, and goes off around the city. In the evening they end up at party hosted by an industrialist who wants Giovanni to write a book about him. Lidia phones the clinic and learns that their friend Tommaso is dead. She then flirts with a guest while Giovanni plays around with Valentina, the twenty year old daughter of the industrialist. A storm rises and Lidia, Giovanni and Valentina end up together in the house. Lydia sees her husband kissing the girl and pretends to be upset. At dawn Lidia seems determined to end the relationship while Giovanni wants to save it. Winner of the Golden Bear at the Berlin Film Festival. Antonioni won a David di Donatello. He was also awarded a Silver Ribbon, as was Monica Vitti for best supporting actress, and Giorgio Gaslini for the music.
