The Devil (1972)

During the Prussian army's invasion of Poland in 1793, a young Polish nobleman, Jakub, is saved from imprisonment by a stranger, who in return wants 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. Becoming apparently demented by what he has seen, he commits a number of seemingly motiveless and gory killings.