After their father (Tim Robbins) is called into work, two young boys, Walter (Josh Hutcherson) and Danny (Jonah Bobo), are left in the care of their teenage sister, Lisa (Kristen Stewart), and told they must stay inside. Walter and Danny, who anticipate a boring day, are shocked when they begin playing Zathura, a space-themed board game, which they realize has mystical powers when their house is shot into space. With the help of an astronaut (Dax Shepard), the boys attempt to return home.