An investigation is being conducted into the murder of Vladan Vidović on the theater stage. The investigation is led by Svetlana, a police inspector, and Žarković, the private inspector of Vladan's father, who used to work for the secret service. Someone with a mask is in the theater, roaming the basement and bent on killing...

There are tense relations in the theater. Many secrets are hidden under the scene. Some hidden people and their secrets come to light. Svetlana and Žarković interrogate the employees of the theater one by one in order to find out the truth. Svetlana confronts the masked killer.