Kim Possible is a high-school cheerleader and world-famous crime fighter, and Ron Stoppable is her faithful sidekick and best friend, who has a pet naked mole-rat named Rufus.

The film begins at the start of a new school year, which Ron has good hopes for, until he finds out he's moving away to Norway for his mother's work.

Meanwhile, Drakken, Killigan, and Monkey Fist turn themselves into children and travel back in time to Kim's first day in pre-school in order to discourage her from becoming a crime-fighter.

Monkey Fist goes into the ancient past and retrieves a giant stone gorilla to attack pre-teen Kim and Ron, but they destroy it with the help of their present-day selves.

Kim's old friend Monique, also a part of the resistance, breaks into the palace to assist her, but the two are eventually defeated while Jim, Tim, Wade, and Rufus 3000 are captured by Killigan and Monkey Fist.

When it passes, Shego's future is erased and the world is restored to its original state, the two teens having lost all memory of the film's events.