Ham III is the grandson of the first chimp astronaut. Soon, the fun-loving chimp has to get serious about the mission - rid a far-away planet of their nefarious leader. Ham III becomes a reluctant hero and learns the true meaning of courage as he and his crewmates, the fearless Lt. Luna and their uptight commander, Titan, risk everything in an effort to save the peaceful inhabitants of a distant planet from the evil dictator Zartog.