A young female gorilla is captured in the mountains of Africa and flown to California, where behavioral researcher Margaret Heller (Helen Shaver) begins teaching her sign language. Heller's moody teenage son, Rick (Will Horneff), bonds with the primate, now nicknamed Katie. When cynical circus owner Gus (Peter Boyle) claims Katie to replace the now-dead star of his centerpiece gorilla act, Rick runs away with the gorilla in an attempt to keep her out of Gus' abusive clutches.