In Milan, Romeo and Alfredo are sold as chimney sweeps to different bosses, having to separate, but not before swearing eternal friendship. Romeo is taken by Rossi, his buyer, to his house, where he will start a new life.

Romeo goes to clean Professor Casella's fireplace who, to thank him, gives him an illustrated book. However, Romeo cannot read, so the teacher offers to teach him to write his name. Upon his return home, he finds a letter left by the girl who lives in the same house, Angeletta. But, how will Romeo know interpret what is written on it?

The carriage Romeo has sneaked into contains explosives that the robbers intend to use to blow up the police station and free their imprisoned friend.

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.