On the Trail of Blood

The story was loosely inspired by a real case from several years ago - the murder of eleven-year-old Josef Neumann. The 24-year-old perpetrator, Jaroslav Papez, met the boy in Prague's Metro cinema, where the man worked as a projectionist. Papez lured the boy into the projection booth under the pretext of watching the film Maigret Sees Red (1963), which was not allowed for children. Papez then abused the boy in the booth and subsequently began stabbing him. At the same moment, the audience in the auditorium was watching the film. However, because the film reel was interrupted during the rampage and unsuspecting spectators began to whistle in displeasure, Papez returned to complete the murder later. He subsequently hid the child's dead body in a shaft under the projection booth. Jaroslav Papez was caught five days after the murder and was sentenced to death during the trial.

When Detective Kalas receives a beer from Vlasta on the table, the foam is up to the rim of the glass. However, when the camera cuts to a view of the courtyard, the foam has suddenly fallen off.