Mighty Joe Young is the story of a young girl called Jill Young, and her pet Gorilla. The film begins with poachers attacking a group of gorillas. Animal preservationists fight the poachers, but this ends in disaster with Jill Young's mother dead, however in the fight the baby Gorilla manages to bite the poacher's thumb and forefinger off.
The film then immediately skips into the future, where Charlize Theron plays the little girl Jill Young, and the Gorilla has grown to 15' tall and weights 2000 pounds. The two have become the best of friends and do everything together.
However things never stay perfect, and the poachers appear again, this time though a representative of a California wildlife refuge, Gregg O'Hara (Bill Paxton), convinces her to transfer the gorilla she has named Joe Young to the refuge. This does not help though as the hunters want revenge, they manage to torment the Gorilla with out the keepers seeing.
The story has many twists eventually having a beautiful ending with quite a romantic feel, and as usual good prevails.