Stalker Sergei Bustrygin (nicknamed Booster), who knows well the part of the St. Petersburg Zone located on Vasilievsky Island, is hired by either a businessman or a bandit Arkady Mamontov. Booster's task is to find Mamontov's missing daughter there. As a result, a small expedition is sent to the Zone, consisting of Booster himself, his student Zheka and those working for the businessman Zoya and Trofim. Taking on the task of fulfilling the order, Booster does not even realize that the search for the girl will lead him to a clash with the special services involved in studying the Zone.