The Devil (1972)

During the Prussian army's invasion to Poland in 1793, a young Polish nobleman, Jakub is saved from the imprisonment by a stranger who wants in return to obtain a list of his fellow conspirators. Following his mysterious savior across the country, Jakub sees the overall chaos and moral corruption including his father's death and the betrayal of his friend who stole his fiancee. Being apparently demented by what he has seen, he commits a number of seemingly motiveless and gory killings.