In post-war Moscow Region, a serial killer appears who cruelly murders teenage girls. The victims become witnesses to terrible mutilations before they die. Olya, a pioneer leader, miraculously avoids the attack, and now her friend Kolya decides to catch the criminal. He is ready to cooperate with the police, set up ambushes, and chase suspicious people. But the killer keeps disappearing every time, never giving himself up. Kolya is already losing hope, but suddenly he gets a chance to stop evil. The atmosphere of the book draws close to the post-war times when young people search for their place in life, and the line between freedom and danger becomes extremely thin.