Jill Young is a girl living in Africa with her mother, a conservationist and gorilla researcher. Poachers kill a mother gorilla, and murder Jill's mother when she tries to stop them. Joe bites off the poacher's thumb and trigger finger. Jill decides to raise the gorilla. She names the gorilla Joe Young. Fast forward 15 years, and Jill (Charlize Theron) is still living in Africa with Joe. Joe has grown into a giant gorilla, 3 times the size of a normal gorilla.
Poachers have seen Joe, and they are obsessed with capturing this immense gorilla. Scientist Gregg O'Hara (Bill Paxton) convinces Jill that the only way Joe will be safe is if they take him to a nature center in America.
Joe is a hit. The poacher from the beginning sees Joe in the news, and realizes that it is the same gorilla who bit off his fingers. He wants revenge. There is a big banquet in the nature center to celebrate the arrival of Joe. The poacher goes and taunts and torments Joe, until Joe goes into a rage and begins destroying everything. Joe is going to be killed as a dangerous animal. The poacher pretends that he has a wildlife refuge in another country where Joe can stay safely. While they are transporting Joe, Jill finally recognizes the poacher as the same man who killed her and Joe's mothers. She crashes the truck, allowing Joe to escape. Joe is loose in the city, hunted by the military.
Joe is attracted to the bright lights of a carnival. Gregg and Jill follow him there. The poacher follows them, and wants to kill both Joe and Jill. The poacher starts a big fire at the carnival. Joe kills the poacher to save Jill. Joe rescues a child trapped at the top of the burning Ferris wheel. Joe becomes a hero, and people donate money to buy land for a special wildlife preserve for Joe.
The movie ends with Joe living happily back in Africa with Jill and Gregg.
Thanks Joseph C!