Marcello Rossi receives a letter from his mother, Mimi, announcing she will pay them a visit soon. Rossi has not seen her mother in a long time, and his memories of her are not very pleasant, so in the beginning he does not like her visiting. On the contrary, Edda and Anselmo, who initially were not very pleased about her coming, are excited after learning that Mimi is bringing a treasure for Anselmo.

Romeo and Angeletta meet the old puppeteer Teo and little Nana. Teo has a sad secret: Leon, his son, left him and his granddaughter after a quarrel. He would rather be a doctor than a puppeteer. Now Teo wishes nothing more than to see his son again. Angeletta asks Romeo and the Black Brothers to find Leon. Also, Matteo is about to reveal a secret about Angeletta to Romeo while talking with Rossi.

Matteo tells the boys the story of Marcello Rossi and Angeletta: a countess named Isabella is the girl's grandmother. Romeo now wants to find out everything and secretly follows Rossi to a castle where the Ice Queen, as Isabella is called by the others, lives.

Angeletta's greatest wish is to meet her grandmother, the Countess Isabella Montovani, before her serious illness progresses. The Black Brothers therefore drive Angeletta to the castle in a wooden cart. Rejected by the security guard, they climb over the wall. They are discovered and there is a chase in the castle courtyard.

Angeletta's condition is deteriorating rapidly. The so-called Ice Queen Montovani wants nothing to do with her granddaughter. Even asking chimney sweep Rossi is useless. The Black Brothers therefore clog the chimneys of Montovani Castle. They want to force the Countess to stay in touch with Angeletta.

In Milan, a wedding of the nobility is taking place and all rich and noble people of the area are invited. Even the king of Italy is expected to come. Then Romeo accidentally meets Bianca, Alfredo's sister who was believed to be missing. When he conveys the good news to him, he learns Alfredo's mysterious story.

Alfredo and Bianca are still on the run from their relatives. Their aunt and uncle want the badge that Alfredo hid. This badge was bestowed on Alfredo's father by Carlo Alberto, the father of the current Italian king, and legitimizes the Martini's fortune.

Professor Casella discovers that Alfredo's illness is worse than initially thought. Alfredo also knows that he will not live much longer. Nevertheless, he firmly intends of showing up before the King of Italy with his sister Bianca to expose his aunt and uncle by showing the king the authentic royal insignia. To achieve this, he thinks up a plan with the help of the Black Brothers to sneak into the duke's wedding banquet.

Alfredo wants to restore his honor before the King of Italy and accuse his aunt and uncle of murdering his parents. Unfortunately, the Wolf Pack lure him into a trap and lock him in the sewers. Romeo and the Black Brothers await his arrival so they can sneak into the banquet, but Romeo, seeing that he does not arrive, decides to go in search of him.

Alfredo and Bianca are still trying to show in front of the King of Italy and expose the damage that has been done to their family. The Wolf Pack has temporarily allied with the Black Brothers and they help carry out this plan together. They have to deal with the bodyguards of Alfredo's uncle so that Alfredo and his sister can sneak into the banquet.

The big moment is here! Alfredo and his uncle Maurizio stand before the king of Italy. Both have badges in their hands, but only one belongs to the Martinis. When the king asks which badge has the secret sign of blessing, only Alfredo knows the right answer. The evil uncle is finally exposed.

Romeo suffers greatly from the sudden death of his friend Alfredo. He sinks into a deep sadness and distances himself more and more from reality. The Black Brothers try to cheer Romeo up again. But even when Dante tries to force him come to his senses, Romeo remains withdrawn.

The circus is coming to town. The Black Brothers want to see it, but they only have enough money for a ticket. Therefore, a competition is held and the winner will go to the circus. However, Romeo as the new leader of the group, makes a wise decision: either all or none. He must come up with a plan to raise the money for everyone. Meanwhile, Michaelo has a mishap with a merchant that puts him in a bind.

While working one day, Romeo falls from a chimney and breaks his leg. Professor Casella agrees to have him at his place until his leg heals. So that means that Romeo and Bianca will spend Christmas together. Romeo challenges to read Alfredo's favorite book, Moby-Dick, while his leg heals. The professor interests them both in many subjects, and Bianca begins to see Professor Casella as a father. They want to thank Professor Casella for his kindness, so they prepare a special show in Christmass Eve.

Spring has fallen and Romeo's contract with Maestro Rossi is over. It is time for Romeo to say goodbye to Milan and return home in Sonogno. Some of his friends have already left, while others still have to stay a while longer. Professor Casella offers to drive Romeo and the other boys halfway to their home towns along with Bianca. Before leaving, they visit Alfredo's grave one last time, where they meet the Wolf Pack.