A chimpanzee performing in a circus goes on a space mission with other chimpanzees and ends up saving the inhabitants on an alien planet. The main character is Ham, the third (with the voice of Andy Samberg). He grandfather was the first Ham and was part of the original efforts to conquer space travel where they first used chimpanzees, instead of humans. Ham performs in a circus being shot out of a cannon on a daily basis. His job is a far cry from the legacy of his grandfather. The space program has sent an unmanned probe, which was lost when it fell into a wormhole. The only way to retrieve the probe is to send trained chimpanzees because the G-force pressures, going through the wormhole, are too great for humans to survive. The probe lands near the home of the alien named Zartog (with the voice of Jeff Daniels). Zartog learns how to control the probe and uses it to take over control of the alien planet. He freezes anyone who opposes him by putting them in a liquid which comes from a volcano. Zartog sees a message from Earth contained in the probe, which shows Las Vegas. Zartog builds a fake Vegas copy from what he learns about Earth.
Ham, Titan (with the voice of Patrick Warburton), and Luna (with the voice of Cheryl Hines) train for the mission. Comet (with the voice of Zack Shada) is a genius chimpanzee. He will stay on Earth providing technical support for the mission. They take a communication device with them made from a banana. The mission launches and the ship goes through the wormhole. They ship crash-lands on Zartog's planet. The three chimpanzees survive the crash, but Titan remains in the ship unconscious. Ham and Luna explore the strange alien planet full of plants, which turn into snake-like monsters. Zartog sends his minions to retrieve the second ship. Ham and Luna are almost killed by the snake-plants and other creatures, right before Zartog's army arrives. Zartog's army using flying beasts to attack the ship and capture it with Titan as well. Ham and Luna barley escape by swinging on the snake vines.
Back on Earth, Comet figures out how to get the communication going, but is only able to hear what Ham and Luna are doing. They have no way to respond back to Comet. The ship is on auto-pilot and will return in one day by itself. Titan wakes up to find he has been captured by Zartog. Zartog wants to kill him, but Titan convinces Zartog he is useful, since Titan knows how to operate the ship. Ham and Luna find a tiny alien named Kilowalawhizasahooha (with the voice of Kristin Chenoweth) which lights up when it is afraid. They call her Kilowatt. She helps them follow Zartog to get their ship back because she wants to get revenge on Zartog for killing her family. They run into some aliens with the appearance of gummy bears. The gummy creatures help them escape an attack by Zartog's men. In a cave, they are attacked by a giant monster which is attracted to Kilowatt as she lights up in fear. She gains her courage to calm down. Nevertheless, she is captured by the monster. Luna and Ham fall through a dream-like cloud which makes Ham express his inner feelings. They make it to Zartog's lair, but are captured. Titan fools Zartog by getting him to use the ejector mechanism allowing them a chance to escape. Zartog recovers and even though the ship is taking off, the chimpanzees decide to stay and help the aliens fight Zartog. Kilowatt shows up to help with the fight, having survived the cave monster attack. Zartog is defeated in a massive battle. Zartog is put in the liquid and frozen solid.
On Earth, they get enough communication power to send a signal and tell the Space Chimps how to make a return ship from the probe. They can use the power of the volcano, when it erupts, to eject them into space. They successfully launch and go back through the wormhole to crash-land on Earth right in the middle of a media event where the Senator is announcing the cancellation of the Space program. The Senator looks like an idiot. The Space Chimps are heroes. Ham and Luna fall in love.
Best part of story, including ending:
This movie is crazy goofy fun.
Best scene in story:
I like the scene when Ham dances with his gummy alien twin and the aliens help them escape Zartog's attack, by turning themselves into a rolling hamster wheel.
Opinion about the main character:
Ham is really fun to watch, especially how he handles the challenges, because he really does not want to be there and never thought he would ever find enough courage or opportunity to live up to his grandfather's legacy.