Poor 10-year-old Lucas Nickle (Zach Tyler Eisen) can’t get a break. Recently moved to a new city with his family, he hasn't made a single friend. He gets nothing but grief from his teenage sister, Tiffany (Allison Mack) and not a whole lot of attention lately from his parents (Cheri Oteri, Larry Miller), who are busy planning their big anniversary weekend trip to Puerto Vallarta. Meanwhile, his loving-but-kooky grandmother, Mommo (Lily Tomlin) spends all her time trying to protect the family from those space aliens she's been reading about in the grocery store magazines. To make matters worse, Lucas has become the number one target of local bully Steve, who never misses an opportunity to push him around.
In turn, Lucas delights in destroying ant hills in his front yard—venting his frustration on the defenseless mounds of dirt and their tiny inhabitants by kicking them, stomping them and squirting them with the garden hose.
But unbeknownst to Lucas, there is a whole world alive and busy just under his feet and what he sees as “just a bunch of stupid ants” are actually members of a complex society, with names and relationships, responsibilities and emotions. They’re getting mighty tired of having their homes trampled by Lucas The Destroyer. And they’re ready to fight back.
The magic potion that Wizard Ant Zoc (Nicolas Cage) has long been working on is finally finished. One drop in Lucas’s gigantic human ear and he is instantly shrunken down to ant size and taken deep below the ant hill to be placed on trial.
Sentenced by the wise Ant Queen (Meryl Streep) to live among the ants and learn their ways to earn his freedom, Lucas finds himself in an incredible landscape suddenly teeming with life—and peril—that he never noticed or even imagined before, and embarks on the adventure of a lifetime.