Jimmy, angry with his parents about grounding him for launching Carl off the roof, decides to run away.

The Yolkians have come to earth, but this time they seek out only peace and brotherhood with the people of Retroville. While Jimmy Neutron suspects the worst, everyone in town is ready to forgive and forget.

Jimmy is enlisted as a spy by the Big Top Secret Organization. His mission: find and rescue Agent X - who turns out to be Jimmy's movie hero, Jet Fusion.

Timmy Turner is magically sent to the secret lab of none other than Jimmy Neutron, the boy with the genius IQ. How will Timmy and Jimmy get back to each other's own worlds?

A strange meteor lands in Retroville, bearing a mysterious message in an alien language. When Jimmy is finally able to translate and answer the riddle, he, Cindy, Libby, Sheen, Carl, Bolbi, and Goddard are sucked into space - only to find that the message is an invitation to Intergalactic Showdown! Team Earth must learn to work together to win - or lose their home planet!