Contemporary Poland. Teenager Zosia Zadora decides to start an adult life. She runs away from home, settles with two friends in the Tri-City. Here she experiences her first love. The sympathizer, twenty-year-old Kostek, turns out to be the head of a criminal group. Zosia's roommates are involved in the procedure. When Kostek is arrested, the girl, after some hesitation, becomes a prostitute. She tries to hide her profession from a young sailor she met, Stefan Janiak, with whom she began to have feelings. One day the man learns the truth.