Mars Needs Moms

Milo is a nine-year-old boy who constantly rebels against his homemaking mother and workaholic father, who himself is leaving for a business trip. Summer is just beginning, and while Milo wants his summer to be fun, his mother assigns him chores. When Milo's mother catches him breaking her "no broccoli, no TV" rule, she grounds him and sends him to bed early. After a heated disagreement with his mother, Milo wishes that he never had a mom. Later that night, his wish comes true when his mother is kidnapped by Martians who plan to steal her "momness" to rear their own young. The Martians, led by their villainous supervisor have been observing Earth mothers, passing up those who are too indulgent or unable to control their children. They select Milo's mother based on her ability to command Milo to take out the trash. To rescue his mom, Milo stows away on a spaceship. Upon arrival on Mars, Milo is locked up in a jail cell, but manages to escape down a garbage chute where he meets a tech-savvy subterranean-dwelling earthling named Gribble. Gribble helps him devise a plan to save Milo's mom and get her back to Earth before Earth's night is up. Unfortunately, the plan goes awry at a Martian checkpoint, when Milo is exposed and the troops raid Gribble's hideout, but Milo is able to escape. While hiding from the guards, Milo meets a rebellious Martian girl named Ki. Milo makes it back to Gribble's hideout, and discovers Gribble has been captured by the Supervisor and the Martians. After rescuing him, Gribble confesses to Milo on how he wound up on Mars: twenty five years ago, the Martians selected Gribble's mother as a fine example to program their nannybots. Like Milo, Gribble stowed away, but failed to rescue his mother in time and was stranded on Mars. After Ki manages to locate Milo and Gribble in an untouched part of the Martian underground world, they come across an ancient cave painting that showed Martian families were like Earth families in the past. After evading the guards and capturing a spaceship, Milo manages to wake up his mother, and save her before the download destroys her, but while escaping out onto the Martian surface, the Supervisor appears, and is about to kill both Milo and his mother when Gribble attacks her, causing her to fire a shot that causes Milo to trip and break his space helmet.

As Milo begins to choke in the unbreathable Martian atmosphere, Milo's mother gives him her space helmet. Although Milo's life is saved, the life of his mother has now been put at stake. Before the eyes of the Martians, Gribble (not wanting to see another Earth boy lose his mother) manages to find the space helmet he'd attempted to save his mom with and gives it to Milo's mother, showing the Martians the one thing they'd overlooked about Earth moms: love for their children, in which Milo apologizes to his mother about the disagreement. The Supervisor attacks the Earthlings again and as she is about to recapture them, Ki reveals the photo of the ancient cave painting and the Supervisor's deception to the soldiers, causing them to turn against the Supervisor.

With the Supervisor in prison, Ki and Gribble return Milo and his mother to Earth, just before Milo's dad returns home. Having nowhere else to go and having exposed feelings for Ki, Gribble decides to stay on Mars and returns there. Milo then takes out the trash before his mother asks him to, but secretly disintegrates it with a Martian weapon, similar to a human pistol in size and shape. Under the new leadership of Gribble and Ki, the male and female Martians work together in raising their young, while the Supervisor is stuck with nanny duty. Gribble manages to contact Milo and let him know how he is by using the Spirit rover as a communication station.