Role in the film
Jill Young is seen as a child at the beginning of the film when she witnesses the death of her mother and famed primatologist Ruth Young, and the mother of Joe, an infant mountain gorilla, at the hands of poachers led by Andrei Strasser. Strasser loses both his right thumb and trigger finger to Joe, and swears revenge on the gorilla for the damage. Before she dies, Ruth tells Jill to take care of Joe, to which Jill agrees.
Twelve years later, Jill has raised Joe who, because of a rare genetic anomaly, has now grown to a height of 16 1/2-feet (5 meters) and weighs 2,200 pounds (1,000 kilograms). As a result, the other gorillas won't accept him and both are now living in relative peace until a wildlife refuge director, Gregg O'Hara, convinces Jill that they would be safer from poachers if they relocate to Los Angeles.
The trio goes to Hollywood, Los Angeles, California and win the hearts of the refuge staff, who are so impressed by Jill's relationship with Joe that they put her in charge of the Gorilla. One day, Jill is approached by Strasser, who is now running a fraudulent Animal Preserve in Botswana while actually selling animal organs on the black market. He has seen a news report about Joe and is now eager for revenge. At first Jill does not realize Strasser was the poacher who killed both her and Joe's mothers, since Strasser's right hand is hidden in his coat pocket. Strasser tries to convince Jill that Joe would be better off in his wildlife refuge back in Africa. Later, during a gala, Strasser's henchman, Garth, uses a poacher's noisemaker to scare Joe into a frenzy. Joe trashes the gala, recognizes Strasser and tries to attack him. Joe is then captured and placed in a concrete bunker. Before their departure, Gregg has fallen in love with Jill and he kisses her goodbye. Shortly after Jill leaves, Gregg discovers a poacher's noisemaker that the maintenance had found, making him realize that Strasser is a poacher and he goes after them to save Jill and Joe.
On the way to the airport, Jill notices the half-glove covering Strasser's missing fingers, and finally realizes who he really is. Just then, Strasser notices Greg pursuing them and pulls out his revolver, but Jill punches him in the chest, then leaps out of the truck and into the street. Joe sees her and rocks the truck over onto its side and escapes. Greg finds Jill, who reveals to him that Strasser killed her mother and plans to kill Joe and they rush off to find him.
Jill and Gregg eventually locate Joe at a carnival where he is playfully wreaking havoc. Strasser arrives and attempts to shoot Jill, but Garth pushes Strasser's gun away from Jill and causes him to fire at a spotlight, subsequently starting a fire and causing the Ferris wheel to break down. Realizing how ruthless Strasser truly is, Garth says that he quits, but Strasser knocks Garth unconscious with his gun. Strasser eventually confronts Jill and attempts to kill her, but Joe sneaks up behind them and tosses Strasser into the air, where he grips onto electrical wires over a transformer. Just before this, Jill, noticing Joe approaching Strasser, coldly tells him goodbye in response. Short two fingers on the hand holding the wire, as he lost his thumb and trigger finger, Strasser is killed when he loses his grip and he falls into the transformer, electrocuting him, and leaving only the half-glove hanging from the wiring.
Later, at the Santa Monica Pier, Joe tries to save a child from atop the burning wheel, but the fire burns it down and Joe and the child fall to the ground, where Joe jumps off of the burning wheel, protecting the boy and knocking himself unconscious as the police cruisers are smashed into chunks. Joe survives the fall and awakens and they mention that they need to raise money to open a preserve for him. The young boy Joe saved donates some change to Jill after hearing this, prompting the rest of the crowd of onlookers to contribute.
Joe is returned to Uganda where Jill and Gregg open the "Joe Young Preserve." In the final scene Joe runs off into the distance, enjoying his newfound freedom.
- Although Jill is the overall protagonist and his bigger plans, Joe drives the plot.