When a travelling troupe threatens to unleash a saucy Berlin revue on the provincial town of Emilsburg, the local Morality Society, a band of sanctimonious middle-aged men, stages a protest. Meanwhile, the reigning monarch is concerned that his son and heir is not living his life to the full. Ninon d’Hauteville, a showgirl and the revue’s star attraction, takes a job as piano teacher to the young prince after her engagement at the local theatre was brought to a premature end, a result of the Morality Society’s interference. It doesn’t take long for those hypocrites to get wind of this. While on the outside they appear to be concerned with running the immoral woman out of their town, behind closed doors they rank among the new piano teacher’s most ardent pupils. However, Ninon, out to right the wrong done against her, secretly keeps a “diary” of their visits, recording each encounter on film with a hidden camera.