One night after shopping, Roxy Miller (Marilyn Manning) is driving to a party through the California desert when she nearly runs her car into Eegah (Richard Kiel), a giant cave man. She tells her boyfriend Tom Nelson (Arch Hall, Jr.), and her father Robert Miller (Arch Hall, Sr.) about the giant. Her father, a writer of adventure books, decides to go into the desert to look for the creature and possibly take a photograph of it. When his helicopter ride fails to show up at his designated pickup time, Tom and Roxy go looking for him. Roxy is soon kidnapped by Eegah and taken back to his cave while Tom searches for her. In Eegah’s cave, Roxy is reunited with her father, who tells her that he has begun to communicate with the caveman and has developed a theory as to the creature’s astounding longevity. When a frisky Eegah expresses what seems to be romantic interest in Roxy, her father, fearful that the creature may kill them both if he is rebuffed, suggests she put up with as much of it as she can bear. Eegah never tries anything too explicit, though, and Roxy even ends up giving him a shave before Tom arrives and helps the Millers escape. Crushed, Eegah follows them back to civilization, a final confrontation ensues, and Eegah is killed.