Carlo, a student about to graduate as a surveyor, and Gabriella, a student at a school for translators, fall deeply in love and decide to get married. The time has come to tell their families the news.
Gabriella's father, Cavalier Antonio Cocozza, owner of a renowned pastry shop, initially seems worried by the news, but in fact fears confrontation with his wife, Matilde. Realising that his daughter is sincerely in love, he devises a plan to obtain his wife's consent.
At Carlo's house, the situation is very different. His father, accountant Giuseppe D'Amore, is categorically opposed to the marriage, mainly for financial reasons. D'Amore's job at the Ministry does not allow him to have enough income to bear the expenses of a wedding. Carlo, who has a deep respect for his father, therefore decides to renounce the marriage, leaving Gabriella and her family devastated.
However, Carlo's mother Teresa tries to persuade her husband to change his mind by showing him an old letter he had written to her when his father opposed their marriage. The letter convinces D'Amore to give his consent to Carlo and Gabriella's marriage.
Once he has obtained his father's consent, Carlo can finally meet Cavalier Cocozza, who agrees to organise the wedding within the next three months.
During the engagement lunch at a trattoria, Cocozza and D'Amore try to agree on the costs of the wedding, but differing opinions lead to a clash and the cancellation of negotiations. This strains relations between the two families and the newlyweds.
Carlo and Gabriella then decide to organise a fake elopement to show their fathers how much they love each other. When the fathers discover the plan, they are forced to give in and consent to the wedding.
To keep his promise, D'Amore joins a building cooperative in his ministry and gets a small flat near the airport of Ciampino, which is a long way from Rome and very small. This causes further tension between the two fathers.
In an attempt to reconcile the two families, Carlo and Gabriella arrange a meeting between Cocozza and D'Amore in Cavalier Cocozza's pastry shop, but the meeting turns into a quarrel. To resolve the situation, Carlo and Gabriella take part in a television programme in which they tell their story and reveal that they are expecting a child. This national scandal forces the two fathers to finally give their consent to marry.
On the day of the wedding, Cocozza and D'Amore realise that they have swapped their wedding clothes and are forced to make a strange exchange in a taxi outside the church. When they arrive at the church, it is too late to stop the wedding, and Carlo and Gabriella are already married. Having no other choice, the two fathers start arguing again in the rain.