The film tells the story of Jerzy, a writer whose creativity has burnt out. His wife and their seven-year-old son Jasiek live far from the city. Jerzy’s enduring creative crisis and their related financial troubles affect the married couple. They are drifting apart and falling out of love. One day, they find out their son is ill and will have to travel to the city for an operation. The long-anticipated journey is exciting for the boy. For the parents, the journey is one of anxiety and separation, which forces them to reflect anew on the essence of their relationship.

Seven policemen, seven deadly sins, a murder case, secrets and the filth of everyday police work: Traffic Department transports the viewer into the darkest Warsaw streets.

When Marcin dies in an accident, his family mourns. However, instead of seeking reconciliation, the relatives of the deceased furiously scratch fresh wounds. The atmosphere in the house thickens with each word spoken because neither the brother nor the parents were prepared for the young man's departure. Mutual relations also become more complicated, and attempts to start a conversation do not lead to an agreement. To make matters worse, the question returns more and more clearly: who is to blame for this death?