In the border town of Matamoros, not far from Texas, the students at the Jose Urbia Lopez elementary school are considered to be the lowest-performing in all of Mexico. The new teacher Sergio Juarez (Eugenio Derbez) takes over the sixth grade and surprises everyone with his "radical" teaching methods in the first lesson. Instead of insisting on discipline and toughness, he treats his students with empathy and openness.

The students slowly begin to find hope in a seemingly hopeless world. In Matamoros, corruption and violence are commonplace even among children. Slums, garbage dumps and gun violence offer few prospects for a fulfilled and happy life. With the unconventional curriculum, however, Sergio hits the nerve of the children. Now one child even dreams of becoming an engineer building rockets for space. However, there is no trace of support or acceptance in the teachers' room and Sergio has to fight a battle against windmills.