In 1770 Austria, servant girl Amie discovers she is a musical prodigy when muses appear to her at the piano, inspiring her first composition. Franz, the celebrated court composer, quickly learns of her talent and offers her a Faustian bargain: elevate her status by composing and playing music, but all her work will be published under the Müller name. She accepts, enjoying months of blissful collaboration with Franz while his mediocre son Georg grows jealous, especially when Amie and Georg's friend Friedrich fall in love. When Georg aggressively confronts Franz with his feelings of frustration, Georg murders his father in a rage, then emotionally blackmails Amie into marrying him and continuing to provide compositions. Throughout it all, Brunhilde—the comedic relief Hausmeister who first took Amie under her wing—remains a grounding presence, watching over Amie with a knowing eye and, when she can, offering small acts of protection from the shadows of the household.

 

Amie endures years of verbal and emotional abuse from Georg until her muses turn dark, driving her to compose a death-march meant for him. She plays the piece, and when Georg asks whose funeral it is for, she answers "yours." After his death, Amie, Friedrich, and Brunhilde panic over the impending concert where Georg was to perform. In a desperate plan, Amie dons Georg's clothes and a Venetian mask, passing as her abusive husband. She invents a story about needing the mask because of a fire accident in order to quiet suspicious gossip. She finally takes the stage herself -- breaking free from her family ties, only to confront an even stronger one -- will the world ever accept a female composer?