In their book, Grand-Guignol: The French Theatre of Horror (2002), Richard J. Hand and Michael Wilson argue that horror plays performed at the Théâtre du Grand-Guignol from the late 19th century to the theatre’s closure in the early 1960s generally oscillated in style between realism and melodrama. The former would prevail during most of the drama, as the “normal” narrative would unfold, until the “moment of horror” when the tone would switch drastically to melodramatic dread. This article argues that a similar shift operates in Quebec horror films, especially those films that deal with Satanism. At “moments of horror,” these films replicate the theatricality of stylized melodrama, breaking with the realism of secure normality. The shift from realism to theatricality is all the more unsettling in French Canadian horror films that Quebec cinema has traditionally tended towards realism and has generally avoided the “fantastique”. This break from the realist tradition of Quebec cinema parallels the films’ break from French Canada’ religious tradition, as moments of horror coincide with moments of blasphemy. Looking at three Quebec “Satanist” films from the past thirty-five years (Le Diable est parmi nous, The Pyx, and Sur le seuil), the author identifies elements of montage and mise-en-scène that represent instances of cinematic theatricality, where the set, the cinematography, the editing, the actor’s gestures and speech, through theatrical artifice, stand out as aberrations within the realistic, Catholic milieu depicted on screen.