Planet 51 - Plot

Plot

On Planet 51, green humanoids with snail-like feelers and pointed ears live peacefully in a society reminiscent of 1950s America, but with alien technology and with 1950s themed space-ships and alien homes. In the town of Glipforg, Lem (Justin Long) is a teenage boy with a new part-time job at the local planetarium and a long-time crush on his neighbor Neera (Jessica Biel). His best friend is Skiff (Seann William Scott), a big fan of the Humaniacs films. At a barbecue Neera's family is having, Lem tries to ask Neera on a date; but her hippie friend, Glar, keeps interrupting with his protest songs.

Just then, a mysterious spacecraft goes into orbit around Planet 51 and sends out a signal. Down on Planet 51, under a secret Army base called "Base 9" (their version of Area 51), there is a basement filled with Earth artifacts including robotic satellites launched by the U.S. and the Soviet Union. The spacecraft's signal activates Rover, a wheeled A.I. probe. Rover escapes, following a program to locate the newly-arrived astronaut. The Planetary Army becomes suspicious after Rover's escape and begins to investigate.

At a barbecue, the mysterious spacecraft touches down in the backyard; and NASA Astronaut Charles "Chuck" Baker (Dwayne Johnson) emerges. As Chuck plants the U.S. flag, he steps on a "rubber ducky" someone left on the ground. Everyone stares, and Chuck tries to get back into his module; but Eckle is in his way, eager for an autograph. Shocked when he realizes he is on an inhabited planet, Chuck runs about wildly and hides at the planetarium as the Army arrives on the scene. Planetary Army General Grawl (Gary Oldman) consults Professor Kipple (John Cleese) about the "alien invader." The Army quarantines the area and asks citizens start a local "civil defense" force to prevent the citizens from becoming "zombies."

At the planetarium, Lem discovers Chuck's hiding-place, and both are surprised to discover they speak the same language. Realizing this alien is no threat, Lem decides to help Chuck, hiding him in his bedroom for the night. Rover finds Chuck, who is very happy to see it. As the General and his men search Lem's room, the group sneaks back into the planetarium with Chuck, who tells Lem he has "the right stuff". Chuck also shows Lem the star that Earth orbits and how the universe is much bigger than Lem had thought, which was that there were 1,000 stars in a universe 500 miles long. The next morning, the Army takes Chuck's module to a secret location.

Lem and Skiff get an idea. The next night is the première of a new "Humaniacs" movie; and Lem, Skiff, and Chuck attend in costumes as fans. Chuck introduces some new music as part of the contest and teaches Lem to dance. Things go well until Rover arrives: chaos ensues. General Grawl arrives and points out Chuck's United States Flag insignia is a dead giveaway that he isn't a "local". Chuck is captured and unmasked. When Lem tries to keep him from being taken away, General Grawl labels Lem a zombie, and Professor Kipple announces he will dissect both their brains. To protect Lem, Chuck pretends to "release" him from his control. Lem is proclaimed a hero, and Chuck and Rover are locked into armored vehicles and taken away.

At Base 9, General Grawl interrogates Chuck, and an accidental gunshot starts a complicated chain reaction with soldiers shooting at each other. General Grawl thinks Chuck is resisting his demands and allows Professor Kipple to have a go at dissecting Chuck's brain. Lem gets his job back at the planetarium and is permitted to speak about the incident on TV, but he cannot truly accept the honor. He feels terrible about Chuck and decides to do the right thing. While he's hot-wiring a car, Neera, Skiff, and Eckle join him to go off to rescue Chuck. The teens know luck is on their side when Rover shows up on the edge of town—he unscrewed the bolts holding together the armored vehicle in which he was imprisoned.

Rover sniffs out Chuck's trail and leads them to an abandoned gas station in the desert. They look around, and Skiff sees a soda bottle in an old refrigerator. When he tries to take it, it opens up the entrance to Base 9. Lem has Glar distract the soldiers guarding the base with his protest group while the rest of them sneak into the base. They find Chuck strapped to a laboratory table, and Professor Kipple is cheerfully getting ready to remove his brain. Lem and his friends break in through the ceiling while Rover scares away the scientists, technicians, and guards. They release Chuck but set off alarms.

Rover helps the group find Chuck's spacecraft, which was in a hangar; but General Grawl warns that, if the "alien" tries to leave, the hangar will blow up. The "alien" does try to leave; and, in the resulting firestorm, the General is knocked unconscious, and most of the soldiers flee. The teenagers and Rover get into the module, but Chuck rescues the General from the fire. Chuck pilots the ship into orbit around the planet, allowing the teens to experience outer space. Skiff and Eckle enjoy the weightlessness; General Grawl realizes Chuck hasn't turned him into a zombie; and Lem asks Neera out on a date. Chuck pilots the module back to the planet's surface; and, although the soldiers are ready to shoot anyone who appears, the General stops them. Finally, the inhabitants of Planet 51 see that Chuck came to their planet for peaceful purposes. Chuck lets Rover stay with Skiff and says his farewells to Planet 51. Chuck then leaves Planet 51 peacefully, accompanied by the pet dog that is owned by a female alien seen throughout the film (Xenomorph Alien), which had sneaked aboard his ship.

During the credits, Professor Kipple emerges from a manhole cover and faces two former patients who drag him off, telling him that he will "love" brain surgery.