Lorenzo Romanini is a real estate agent and a classic "big baby" who still lives with his parents and refuses to move out on his own, much to his father Maurizio's despair. Piero Mistico is a single radio host who, to avoid a relationship, tells his girlfriends Cinzia and Sandra that he's married and has a child. Virgilio has a struggling DVD rental business and had a falling out with his best friend Piero in high school. Francesca Coppetti, a successful chef, undergoes sessions to "cure" her sex addiction and is saved by her tutor Gianni while she's kissing her colleague Amodeo in the car after dinner. Luisa Cappiello is a very confused single mother who is on the verge of becoming an architect. Serena Serafini is a rich and spoiled woman whose husband has been targeted by the Guardia di Finanza, while her daughter Lucrezia is having an affair with Savino, the son of an ATAC bus driver and therefore not of their social class.

Serena is completely broke and living in a boarding house, but she's not supposed to know. When her daughter is caught stealing money from a classmate, she starts making deliveries to Mimmo "the Frenchman." Piero struggles to manage the two lovers and finally manages to come clean to Virgilio about the fact that he hadn't actually slept with his girlfriend Anita twenty years earlier. Lorenzo and Luisa, using the excuse of studying, begin spending a lot of time together, but neither can bring themselves to make the first move. Meanwhile, Francesca is obsessed with her new math teacher, Daniele Di Giulio. The group decides to pressure Professor Russo, but then, in a fake robbery attempt, Piero gets the worst of it when she punches him and ends up in the hospital. There, they also find Di Giulio, who was brought there by Francesca after being attacked by thugs outside his restaurant.

The students are specially quizzed by Professor Russo, and they all get top marks in philosophy. Serena enjoys working with Mimmo. Piero is having trouble because Sandra is harassing him, while Cinzia demands a photo of her supposed son, so she shows him a photo of Virgilio's daughter as a child. Lorenzo and Luisa arrange to meet on the tram to find their soul mate. Virgilio returns home to get some things and leaves without explaining himself to his wife; meanwhile, he begins to feel good about Doriana. Professor Russo begins to take care of Simona Fabbri, a difficult student, but must also face her own problems. Professor Di Giulio returns to class and helps Francesca with her assignment; outside of school, however, the student harshly scolds him. The day of the teachers' parent-teacher meeting arrives.

The school is occupied during assembly, and Piero makes amends with Russo, subsequently making her escape through a side exit in exchange for a C in history for the entire class. The teacher is reluctant to continue dancing late at night and continues to deal with student Simona's problems. All the "grown-ups" participate in the occupation, including Serena, who then leaves and spends the night with Gigi wandering around Rome, while Lorenzo and Luisa have a heated argument. During the class meeting, Russo defends Simona, clashing with her colleague Formighi. Di Giulio's addiction problems are worsening, and while inquiring about getting help from a psychologist at the center, he spots Francesca, who hasn't had sex for six months. One evening at dinner, he confesses his problem to her, convinced that she is an alcoholic.

The various protagonists' romantic endeavors seem to be in vain: Gigi and Serena argue because Serena has hidden from him the news that her ex-husband has abandoned her and their daughter without savings. Doriana is disappointed and frightened by the age difference after discovering that her mysterious suitor is Virgilio. Lorenzo and Luisa are increasingly distracted by their new suitors. Finally, Piero continues to seduce his current lovers. But on a trip to the beautiful city of Noto, Cupid's arrow strikes again.

As soon as he returns home, Lorenzo develops a severe psychosomatic fever: he's tormented by his inability to say the right words to Luisa after their wonderful night in Sicily. Meanwhile, surprisingly, Serena pushes Gigi away and tries again with Giuseppe, thus resuming the comfortable life she once led. Serena is perplexed and angry, but for now, she's putting a brave face on things. However, it's the breakup between Serena and Gigi that finally strains the relationship between Savino and Lucrezia.

The "old high school students" are admitted to the exams, but despite the principal's recommendations to commit seriously, they focus almost exclusively on their romantic issues: Piero is sorry for what happened with Claudia, but she just doesn't want to hear from him anymore. Daniele suddenly breaks up with Francesca after discovering her addiction. Serena loves Gigi and manages to make amends, but she discovers she's pregnant and they separate again. Luisa and Lorenzo also go back to being just friends.

A few days before graduation, the veterans move into the same beach house where they stayed as teenagers, before their first exams. The six friends discuss what they longed for as teenagers and what they've achieved. As for love, no one is happy. Serena has decided to move to Dubai with her husband. Virgilio breaks up with Doriana. Daniele is tempted to gamble again, and Luisa is certain of Flavio's infidelity. It will be a very tormented night before the exams.