The Blue Angel (1930)

Based on Heinrich Mann's novel "Professor Unrat". Immanuel Rath (Emil Jannings) is a provincial prep school teacher who becomes incensed when he learns his boys have become infatuated with Lola Lola (Marlene Dietrich), a cabaret singer. Heading to the Blue Angel, a nightclub, to catch his pupils, Rath instead becomes bewitched by the sensuous Lola himself, beginning an obsession that drives him to the depths of despair.