The plot revolves around a picture – a father and a son, Sigmund and Pavel. Together, these inhabitants of Poland administer a small family business importing second-hand clothing from France to Poland. Once back from another such trip, Pavel inadvertently draws attention to the tabloid with a portrait of his father. The author argues that Sigmund, a member of "Solidarity" movement, has always been considered a true hero, a real fighter against totalitarianism – a confidential informant of the communist regime, a rat. What follows this message destroys the usual family life. Friends and relatives turn away from Sigmund, he is labeled as a "traitor". Pavel decides to look into the matter and find the truth. However, the deeper the hero of the film "The Mole" is immersed in the family history, the more secrets he opens that he would prefer not to know...