Horrificator.Nino is filming a movie in his classroom for a film contest, but Mylène, one of the actors, is unsure about her ability as the leading actress, as she is easily frightened. After many failed attempts of shooting a single scene, Chloé makes fun of Mylène's fear and she flee the classroom in tears. Disappointed in herself, Mylène is influenced by Hawk Moth and mutates into "Horrificatior", a slimy monster based on the one from Nino's film, who scares people and feeds on their fear. For Ladybug and Cat Noir to shrink the monster, they must conquer their own fears.