Sydney Sweeney (Everyone but You, Euphoria, The White Lotus) plays Cecilia, a deeply religious young American nun who is called to move to a remote convent in the beautiful Italian countryside. What seems like a warm welcome quickly turns into a nightmare when Cecilia discovers that the convent harbors dark secrets and unnameable horrors. Within the ancient walls lurk malevolent forces that threaten to drag her into the abyss of madness.