After the body of a local student is found in a forest, the police discover that she was murdered. New teacher Pawel Zawadzki arrives at her school, but his reason for leaving his city job is unclear.
Students reveal Joanna was unpopular, and the police tell her boyfriend Maciek that she was pregnant. Ewa, Joanna's mother, is shocked to see her daughter's biological father, Pawel, at the funeral.
Daniel, the PE coach at the school, is arrested by the police, but Pawel finds evidence to clear him. Shady local businessman Grzegorz Molenda holds a party, and Maciek finds a video of Joanna.
The video convinces Maciek that Grzegorz's eldest son, Sebastian, is the murderer so he steals a gun. Sebastian's brother, Jasiek, tries to become part of a gang led by Adrian, Grzegorz's sidekick.
Sebastian and Pawel exchange favours to play down Maciek's shooting. Grzegorz works on an illicit deal. The prosecutor orders DNA and blood tests from the Molendas to see who fathered Joanna's child.
Grzegorz is arrested for Joanna's murder after his plan to have the blood samples switched is uncovered. Ewelina, Joanna's close friend, discovers that the land Grzegorz wants to sell is polluted.
Ewa's testimony clears Grzegorz as he visited her on the night of Joanna's death. And Pawel confronts gangster Yuri to discover whether Adrian and his thugs were involved in the murder.
After Adrian saves Pawel from Yuri, they agree to work together to track down the killers. Meanwhile, Grzegorz has plans to put a stop to Adrian's relationship with his daughter, Julka.
Pawel believes that more people are involved in Joanna's death than just Kijana and Shrek. The story about the ecological damage in the forest destroys the chances of Grzegorz's dodgy deal succeeding.
Jasiek's drugs destroy one student's chances in an inter-school competition. Pawel is sacked from his job but discovers that Ewelina and Julka are implicated in the events leading up to the murder.