Filippo Ferrari and Carmine Di Salvo come from two different backgrounds. The first is from Milan, wealthy and a talented pianist. The second is Neapolitan and belongs to a family of the "system" but, unlike his parents, he has chosen an honest job and his dream is to be a hairdresser. But fate has decided to trip both of them up: Filippo and Carmine find themselves sharing the same cell in a juvenile detention centre in Naples. Filippo, after a night of MDMA at the disco with his friends, finds himself on top of a tower to challenge his best friend in a test of courage. Unfortunately the challenge ends in tragedy and Filippo is accused of murder. Carmine, on the other hand, when one of the boys from the rival clan tries to rape his girlfriend, kills him with hairdresser's scissors.

Carmine and Filippo enter the Juvenile Detention Institute. Carmine knows the rules, while Filippo seems to have landed on another planet. He is immediately nicknamed 'o Chiattillo (The Young Master) by the other boys. Ciro, the boss of the convicts, seems intrigued by Chiattillo and in exchange for his services offers him his protection. Meanwhile, Carmine is brutally beaten up by one of Ciro's henchmen, Pino. Commander Massimo doesn't seem to worry too much: when new elements join a group - already complex in itself - there are always aftershocks. It's in these moments that you have to be vigilant without intervening. The headmistress, Paola Vinci, is not of the same opinion and punishes the boys. Filippo, convinced that the magistrate is about to put him under house arrest, refuses Ciro's protection and does not follow his orders. In response, Filippo is subjected to yet another humiliation at the canteen and reacts by offending Ciro and his henchmen.

A new character enters the prison: Naditza, a regular at WM. Nad has herself arrested to escape the fate her family has decided for her: to marry her in exchange for money to a cousin twenty years her senior. Nad plays the piano like Filippo and makes a bet with the other inmates: within a few days the Chiattillo will drool at her feet. Ciro can't wait to avenge the death of Nazzario Valletta, killed by Carmine, who feels the noose around his neck: everything he wanted to get away from has come true, he is now a prisoner with a death threat on his head. Filippo in prison awkwardly tries to catch up with Ciro and his affiliates, boasting of being there for having committed a crime of honour by killing an infamous man, but when Pino 'O Pazzo discovers that the Chiattillo told a lie for him things get bad.

The spotlight is on Viola, an icy girl serving a sentence for murder with the aggravating circumstance of cruelty. The girl is charismatic and Ciro himself suffers from her magnetic charm. Naditza comes into conflict with her and tries to free other inmates from her "yoke". Matron Paola has a new project for the WM: to have the boys participate in recreational activities together with the girls. Commander Massimo is against it while Beppe proposes a music course: Naditza can play but has never studied, Cardiotrap can sing but doesn't know music, Filippo could be a teacher. The first lesson does not go as hoped. To appease Pino's aggression towards him, Filippo does the last thing he should do: he buys him a present. Pino thanks him, but soon the others demand the same treatment and when their requests are not met, trouble begins.

Gemma, a girl from Rimini, habitually suffers violence from her boyfriend, but when her sister becomes a victim herself in order to defend her, revenge seems to Gemma to be the only way to heal her sick love. Revenge is also what Filippo is meditating on, as he won't resign himself to the abuse Pino is subjecting him to. Now he has a weapon and has every intention of using it in his defence. Carmine, on the other hand, has been reborn after hearing the news that he is soon to be a father. He cannot lose hope because he has a reason to fight. But Carmine is still threatened with revenge by the Vallettas. In the meantime, the headmistress is informed of the disappearance of the razor blade stolen by Filippo and suspends both permits and recreational activities. This fuels anger among the inmates who think Carmine is responsible.

Edoardo goes out on leave. Filippo gives the razor blade to the director, but Paola can't get him to reveal who he was defending himself against. Ciro learns that it was Filippo who stole the razor blade. Pino wants to teach him a lesson, but Ciro seems to have something else in mind for Chiattillo. Filippo takes Ciro's bait and accepts his protection. Carmine warns him: the friendship that Ciro is offering him is called "belonging" to the "system": one is indebted for every favour received. Carmine is right and in fact Ciro asks Filippo for a test of courage to obtain his protection. In the meantime Gemma enters the feminine world and Viola starts to manipulate her with her manipulative art...

The friendship between Filippo and Carmine is in crisis just when they need each other. Filippo is not long in discovering the price of Ciro's protection: during his leave he will meet his family in a restaurant. Edoardo takes advantage of the activity at the pottery workshop to court Teresa in his own way. Gemma, during her conversations with her mother, discovers her sister's deterioration and sinks into a state of guilt; Viola, meanwhile, sensing her weakness, keeps circling around her.

Massimo continues to keep a close eye on Carmine and suspects nothing of the order he has received. He sees himself in him, tells him his story, how sometimes it is difficult to make the right choice because it involves a very high price to pay. Meanwhile Filippo has met his parents in Naples, he has to obey Ciro and put his father's car at the disposal of the young boss' friends.

Filippo returns to the Institute after completing his operation and tries to get closer to Carmine. Edoardo writes a beautiful poem inspired by Teresa, to try to take part in a competition and obtain a permit award. Viola is able to manoeuvre Gemma and pushes her towards the boyfriend she tried to kill to avenge her sister.

The days pass and for Carmine the situation becomes more and more difficult: he has to kill Massimo or he will pay with his life. Nina and her son are also in danger, Filippo is close to them and promises that they will find a way out. Naditza can't get Filippo out of her mind and feverishly takes up playing, perhaps to feel closer to him and cultivate hope for their love. Edoardo makes it to the finals of the poetry competition and hopes to have his wish granted.

Massimo and Paola are desperately searching for Carmine and an intuition leads them to the port. Here they meet Carmine, who manages to hide himself in a daring way; Carmine could kill Massimo from his hiding place, but he refuses to obey the laws of the Camorra and flees, joining Nina on board the ship that is about to set sail to take them illegally abroad. Meanwhile, in the Juvenile Detention Institute, Ciro begins to doubt that it was Pino who stole the drugs from Filippo's car and carries out a small investigation to discover that the plan was hatched by Carmine and Filippo. The furious young boss promises revenge. Filippo is in grave danger and Naditza senses that Ciro wants to kill him. The only way to save him is for Filippo to end up in solitary confinement and Nad has the right idea: a transgression that will mark the peak of their love but will perhaps drive them apart forever.

Carmine has returned to the IPM and joins Filippo in solitary confinement. They know what they risk and Carmine wants Filippo to tell the truth and save himself. Filippo does not agree, they will stay together until the end because together they now feel invincible. Ciro organises a revolt to get Carmine and Filippo in solitary confinement and manages to occupy the Institute canteen. Massimo, however, understands Ciro's intentions and rushes to move the two boys from solitary confinement to the ceramics workshop. Ciro takes Paola hostage and threatens to kill her if she doesn't tell him where Carmine and Filippo are hiding. Massimo tries to save her but it is Beppe who gives in and reveals their whereabouts. It's a showdown.

Carmine is suspended between life and death, but Nina doesn't give up, convinced that to have a future you have to create one. Massimo, crushed by a sense of guilt, decides to leave his post as commander and Paola finds herself alone to face the boys.

Sasà, a young man from Naples, enters an institution for a crime that is not revealed. He becomes a new target. Naditza is about to leave and Filippo convinces his family to put her up in Milan.

Naditza leaves and, unbeknownst to her parents, is placed in the care of Filippo's family, while waiting for him to be transferred to Milan. Cardiotrap gets closer and closer to Gemma. Lino is lured by the rich and charming mother of Sasà, the young boy from Naples. Kubra enters the IPM, her mother is African and she is a first generation Italian.

The magistrate arranges for Carmine to return to the institute, but the boy does not want his daughter to be a Di Salvo and entrusts her to Nina's mother. His family is at war with the Riccis. Filippo is transferred to Milan where Nad is waiting for him. To say goodbye to him, Beppe organises a concert where Cardio sings the songs he wrote with Gemma. Pino is attracted to Kubra, but the girl is hostile to everyone.

We discover that in the past Beppe had a relationship with a black girl, Latifah. Kubra takes him back to those days. Nad feels rejected by Filippo. Cardiotrap receives good news: his father has organised his first concert. Massimo resumes his command post to be near Carmine.

Paola manages to get custody of little Futura. Edo and his family discover that Sasà is in jail for rape and they don't give him a break. Luisa, in order to protect her son, deceives Lino. Kubra, in order to protect Silvia, ends up in solitary confinement and Beppe succeeds in extracting from her shocking confidences. Edoardo's anger grows because Teresa has disappeared. Nad receives a very unwelcome visit in Milan.

Massimo, after discovering that Nina's murderer is in the IPM, decides to do his own thing and puts the suspects in solitary confinement to try to discover the truth. Carmine suspects something and is more and more agitated while Filippo has other thoughts: Naditza has returned to the institute and is very angry with him, will he be able to win her back? Meanwhile, Beppe discovers an important truth about his past.

Massimo continues his investigation and discovers who is guilty of Nina's murder but in the meantime he has to face a sudden family crisis. Carmine and Filippo try to figure out who the culprit might be while Filippo and Nad seem to be in a good place, but Pino's rash action puts everything in question.

Carmine realises who the culprit of the murder is and obtains a weapon to kill him while the memory of Nina torments him. Filippo tries to clear things up with Naditza. Edoardo goes on leave for his son's christening, but first he goes to see Teresa, whom he sees in the company of another boy.

Carmine devises a plan with Pino's help to get Pirucchio out of isolation. Filippo senses what's going on and disowns Carmine as a friend to shake him from his revenge intentions. Gemma reads the letter Fabio sent her and struggles with her feelings for him. Filippo and Naditza are further and further apart because the girl has agreed to marry one of his cousins.

Carmine, face to face with Pirucchio, has a crisis of conscience and fails to kill him. In the meantime Massimo discovers that he is not the real culprit. Filippo and Carmine decide to flee using the plan they have organised for Edoardo, but they don't know that Wanda Di Salvo is behind the plan and wants to kill Edoardo. Their lives are now in danger.

Filippo and Carmine, who have escaped Edoardo's execution, rush in to prevent Naditza's wedding. Ciro's sister Rosa enters the prison and reveals to Edoardo that Mimmo is a traitor. The girl threatens Carmine, who has returned to the IPM in the meantime. Cardiotrap, who has learned that Gemma has seen Fabio, runs to the boy and is determined to end this relationship once and for all. Love bells ring louder and louder between Kubra and Pino.