The film is based on Christine Leunens's 2004 novel "Caging Skies" and tells the story of Johannes "Jojo" Betzler (Roman Griffin Davis), a 10-year-old German boy who is a devoted member of the Hitler Youth. As the war intensifies, Jojo discovers that his mother (Scarlett Johansson) is hiding a Jewish girl, Elsa Korr (Thomasin McKenzie), in their attic. This discovery sparks a crisis of conscience for Jojo, who must confront the harsh realities of war, Nazi ideology, and his own identity.