Let Him Face the Music! (1978) on Netflix

The song "Ribwort and Rosemary" by Ales Brabec (Ludek Sobota), a shy supply teacher of musical school, wins the music festival in Krumlov. The song interpreter Marcela (Helena Vondrácková) from a Prague Theatre in Underground realizes that such songs would be exactly what their theatre needs. Ales firstly hesitates, but finding out that his fiancée has just left him, he decides to grasp the chance and leave to Prague with Marcela. The theatre needs several songs to be ready for a new play, so Ales has all the possible conditions and comfort to compose, he falls in love with Marcela instead, staring vacantly and doing nothing. The theatre manager's wife, a student of psychology, is convinced that what Ales needs to compose good songs is not peace and silence, but fear. So, the manager decides to turn Ales's life into horror.