Most of her colleagues take Mária, the new teacher to be a communist party-worker, only Irma and the drawing teacher Zoli treat her kindly. Mária starts working with great enthusiasm, and her class learns to love her in a short time.

This entertaining film highlights the importance of integrity, justice, and appreciation for the environment. The compassionate and wise Captain is the hero, who is trying to stop long-time troublemaker and master of disguise Zero the Cat as he plans his biggest coup ever. Helping the Captain along the way are the bright Constable Eleméri Ede and seasoned secret agent Góliát. The resourceful Gólíat succeeds in locating Zero's hiding place, where he overhears part of Zero's newest plan. Although unable to get all the details, Gólíat reports to the station and it becomes clear that stopping Zero will be quite a challenge.