After a series of tests, Jacinta and Héctor confirm their suspicions: Paula is Irene Espí's daughter, who has been kidnapped by the old professor; Elsa is planning to expel Marcos and Paula from school.

The professor surprises the kids while they were carrying out a search of Mateo's room; Mateo tries to pick a fight with Marcos and Iván, and Iván ends up knocking him out.