After their father is called into work, two young boys, Walter and Danny, are left in the care of their teenage sister, Lisa, 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, the boys attempt to return home.

To test its top-secret Human Hibernation Project, the Pentagon picks the most average Americans it can find - an Army private and a prostitute - and sends them to the year 2505 after a series of freak events. But when they arrive, they find a civilization so dumbed-down that they're the smartest people around.