August in an anonymous and working-class neighbourhood of Milan. Gianni is a profoundly unhappy young man because his twin brother, Moreno, lives in an institution for the mentally handicapped.
Their father, Anselmo, a blue-collar worker in his fifties is a widower with neither the will nor the means to care for his sons. Gianni lives alone and works at a petrol pump. He spends what free time he has visiting Moreno and going out with his girlfriend, Betty. Gianni and Moreno are extremely close. Betty is also in her twenties. As well as being unemployed, she has a difficult relationship with her mother, Cristina because of the older woman’s relationship with Riccardo an unscrupulous architect.
Gianni gradually pulls Betty into his obsession to bring Moreno back home and care for him there. The situation precipitates when Anselmo signs over the custody of Moreno to the institution where he lives. Gianni is shocked because he realises that the only way of convincing Anselmi that Gianni and Betty will be able to care for poor Moreno is if he can lay his hands on a very large sum of money straight away.
There is a robbery at the petrol pump and Gianni watches it happen almost as if he were hypnotised. The thieves make their escape but one of them loses his handgun which Gianni picks up. In the meantime Betty’s relationship with her mother is deteriorating fast.
One evening Betty convinces Riccardo to take her out and they end up making love in his car. She hates his ambiguity and would love her mother, Cristina to drop him. When Cristina discovers what has happened, Betty turns to Gianni for advice. He takes the news of her tryst with Riccardo badly but his anger does not last and he accompanies her to an interview for a job in a supermarket. Without any warning, Gianni draws the pistol and threatens the supermarket manager. A glance at Betty tells him that she understands what he is doing and will play along. They get the hapless manager to hand over the takings and escape into the crowded streets. They run all the way to Anselmo’s, show him the money and convince him to bring Moreno home. At last Gianni and his twin brother are together again and the boy experience a sensation of liberty in the empty city. Gianni takes Moreno to work at odd jobs like cleaning windscreens and the like. Meanwhile Riccardo tells Cristina that he is leaving her and she goes to Gianni’s to speak with Betty. It’s not much, but it is a tangible sign that the relationship between the mother and daughter is back on track. Moreno does not understand the complexity of the relationships that surround him and tells both Betty and Cristina that he loves them. After her reconciliation with Cristina, Betty decides to go to Riccardo’s and kill him, but...