Sofia, their new classmate, is a very shy girl in need of self-esteem boost. Valentina offers to teach her how to be more confident, but when Tommy asks her out, Sofia ends up outshining her teacher. Nico finds a treasure map that he thinks belong to by Sir Manzoni. At night, Nico, Tinelli, Annina, Smilzo, and Tommy go treasure hunting. After a struggle, they retrieve a treasure chest and find a recorder inside. When they play it, they hear a familiar voice, and find themselves getting called into the principal's office!

During her P.E. lesson, Valentina falls down and breaks one of her teeth. To show his support, Tinelli intentionally breaks his two front teeth. Unfortunately for him, Valentina gets her tooth repaired and can't stand the sight of a toothless Tinelli. Secchia decides to become a rockstar so that he can impress Mafalda. Nico supports him and offers him some fashion advice. Secchia then plays a song by The Rut, Mafalda's favorite rock band. But when things don't go as planned, Secchia fails once again.

Tinelli is upset with his poor grades so asks Dred to help him pass Mrs. Martinelli's test. Dred, who sits in front of him, writes all the answers on his back. Unfortunately, Mrs. Martinelli catches them red-handed, and they both get called into the principal's office. Bella decides to give most of her clothes away to charity, and Valentina becomes jealous of everyone admiring her. Valentina decides to set up a stall to sell her own clothes, with the proceeds also going to charity. However, when Bella buys everything she's selling and Valentina sees her wearing one of her outfits, she gets so mad she forces Bella to return everything she's bought.

Tinelli is extremely jealous of Nico. Annina, his little sister, nominated him as her new brother because he makes her laugh all the time. Tinelli decides to fight back, but just when it seems like he's about to win, Annina chooses Dred over him. After a trip to the dentist, Smilzo can't eat any solid food. Secchia introduces him to one of his inventions, a liquidizer that makes any food into a liquid. Smilzo secretly decides to liquidize his grammar book and drink it, hoping he will absorb the information within it.

Secchia has come up with the perfect formula to set off a chain reaction of good deeds. Everything starts with Tinelli, who asks Secchia to get him a date with Valentina. Valentina accepts it only if Tommy accepts to go out with her, and Tommy accepts it only if Bella accepts to go out with him, and so on. Eventually, Secchia's plan turns out to be unpredictably complicated. The girls form a "Down with the Boys" club. The boys then decide to take revenge by stealing their mascot. Smilzo disguises himself as a little girl and pretends to be part of another girls club to persuade them to exchange mascots, but he ends up betraying himself with his unmistakable laugh.

To punish the students, Mrs. Martinelli bans recess. Students are now forced to stay in class, and if someone stands up, a weight sensor placed under their chairs goes off. Nico comes up with a plan to trick the sensors and makes Smilzo sit on top of a pile of chairs, but they get found out and called to the principal's office. Valentina needs a male model to wear her outfits for her new fashion venture. After a few failed attempts, she’s forced to ask Tinelli for help. However, her outfit is so terrible he's too ashamed to wear it. Tommy and Dred suggest that Valentina should move on to children's fashion instead. Unfortunately for Tinelli, she still wants him as her model.