The film was based on the life of a gorilla called Massa with elements of Gertrude Lintz's other gorilla Gargantua (who was called "Buddy" at the time). In real life, Massa became the oldest Gorilla on record while Buddy/Gargantua died young as a circus attraction and his remains are now on display in a museum.
Millionaire animal lover and overall spoiled rich girl Trudy (Rene Russo) adds the title animal, a gorilla, to her family. The ape named Buddy finds life in the city very difficult to deal with. Although Trudy raises him as her own son in her mansion (which also houses a few comical chimpanzees, a kitten, a horse, her prize-winning champion pack of Briards, a raccoon and a flock of geese), he becomes hard to control due to his strength. A particularly bad experience in the ChicagoWorld's Fair makes things even harder for Buddy.