The existence of Niccolò, a film director living in Rome, is empty. He has no new film to make, no woman in his life, and his only family is his sister, a gynaecologist, and her little son. He approaches one of his sister’s patients, a beautiful young aristocrat called Mavi, and the two start a passionate affair.
It proves empty, since Niccolò has no interest in her family and titled friends, a feeling they reciprocate, and introduces her to no friends of his. Worse, Niccolò finds he is under surveillance and is even explicitly warned off Mavi. Who these threats emerge from she does not say and he never finds out. To escape his shadowers in Rome, he takes Mavi out to an old farmhouse he has rented, but the drive there through fog is traumatic and they quarrel violently. In the morning Mavi has vanished. Searching for her back in Rome, the only friend of hers who will talk to him warns Niccolò that Mavi is bisexual and hints at a jealous past lover.
Wanting company and affection, Niccolò meets a young stage actress called Ida, slim and athletic like Mavi, a working-class girl who loves the country and is not brittle or mysterious but utterly open. While she is happy to sleep with him, she realises that he is still longing for Mavi and sets him on the trail to find her present address. Listening on the stairs, Niccolò hears Mavi tell the girl with whom she shares a flat that she must keep on hiding from him.
Accepting at last that Mavi will never come back, he takes Ida for a romantic holiday in Venice. There she gets a phone call from her doctor in Rome, who confirms that she is pregnant. Delicately, she tells Niccolò that she does love him but her loyalty must now be to the father of the baby.
Back alone in Rome, Niccolò starts musing about his next film. He imagines a spaceship built of asteroid material that could approach the sun. He recalls telling his young nephew about space travel, saying, “The day mankind understands what the sun is made of and its power, perhaps we’ll understand the entire universe and the reasons behind so many things.” His nephew responded, “And then?”