An old and forgotten game develops magical powers in this fantasy for the whole family. Twelve-year-old Walter Budwing (Josh Hutcherson) and his younger brother, Danny (Jonah Bobo), figure they’re going to be in for a boring time when their father (Tim Robbins), who was supposed to spend the day with them, is suddenly called away on business, and gives them strict orders not to leave the house. Walter, who doesn’t have much use for Danny, is motivated by boredom more than anything else when he agrees to play a board game Danny has found in the basement during a round of hide-and-seek. However, the boys quickly discover the space-themed game Zathura has some unusual qualities — a roll of the dice unexpectedly launches the Budwing home into outer space, and Walter and Danny are suddenly fending off menacing robots, angry aliens, and showers of interstellar debris outside the Earth’s atmosphere. As the boys try to figure out a way back home, they get some unexpected help from an earthling astronaut (Dax Shepard) who has also lost his way.

Bored to death, the always bickering siblings, Walter, and his six-year-old brother, Danny, unearth a forgotten 1950s space-adventure board game in the dusty basement. Without delay, the boys start playing the game, and before they know it, a violent meteor shower wrecks the living-room, and the mysterious game uproots their entire house, turning it into an extraordinary spaceship on its way to Saturn. Now, whether they like it or not, the brothers, along with their teenage sister, Lisa, will have to figure out a way to work together; escape from the dangerous asteroid zone, and survive the onslaught of the ferocious reptilian race, the Zorgons. Can they win the challenging game, and return home in one piece.