At the age of 50, Merlí Bergeron (Francesc Orella), a philosophy teacher, is transferred to Angel Guimera High School. Although his arrival is far from unanimous, he quickly manages to win the sympathy of his students, thanks to his very accessible approach to the subject he teaches. As for the teachers, they only moderately appreciate his work methods.
At home, Merlí tries to regain her relationship with Bruno (David Solans), her teenage son.