The U.S. government grows worried for the nation’s avocado supply after some confrontations with the “Piranha” tribe of cannibal women, who live in the mysterious “Avocado Jungle” (westernmost outpost: San Bernardino) and ritually sacrifice and eat men. The government recruits Margo Hunt (Tweed), a professor of feminist studies at a local university (“Spritzer College”), to travel into the Avocado Jungle and make contact with the women to attempt to convince them to move to a reservation/condo in Malibu. Along the way, she and her travelling companions — male chauvinist guide Jim (Maher) and ditzy undergraduate Bunny (Karen Mistal) — meet a tribe of subservient men called the “Donnahew” (a reference to talk-show host Phil Donahue) and face dangers in their path.
Eventually, the trio (Margo, Bunny and Jim) meets the Piranha women, who have recently taken Dr. Kurtz (played by Adrienne Barbeau) as their “empress.” Kurtz is Dr. Hunt’s former colleague in feminist studies (the internationally famous author of Smart Women, Stupid Insensitive Men) and now her nemesis; she has joined the tribe of Piranha women with her own exploitative agenda. The two argue about the morality of sacrificing men and the exploitation of the Piranha women, and Bunny decides to join the tribe, her first sacrifice being Jim. Bunny cannot go through with the kill, however, and Dr. Hunt escapes, aided by the handsome, intelligent, and sensitive Jean-Pierre (Brett Stimely), who also was to be sacrificed.
Dr. Margo Hunt finds in the jungle a rival tribe of cannibal women, the Barracuda Women, who are at war with the Piranha women due to differences over which condiment (guacamole or clam dip) most appropriately accompanies a meal of sacrificed man. Hunt returns to the Piranha stronghold with this other tribe and rescues Bunny and Jim as well as Jean-Pierre.
Margo Hunt challenges Kurtz to a duel for supremacy, and they argue while fighting with various weapons; eventually, Margo impales Kurtz with a fencing sword. Kurtz explains her motives to Hunt in her last words: After ruling the Piranha tribe, she cannot return to civilization and the talk-show circuit. She then kills herself by plunging into a pit filled with water and piranha fish.
Having discovered the government plot to domesticate the Piranha women by providing aerobics classes and frequent exposure to Cosmopolitan magazine, Hunt refuses to bring the Piranha women with her, and instead persuades the warring cannibal tribes to reunite, maintaining the peace by means of consciousness raising groups.
The film ends happily for the trio of main characters: Bunny and Jim are to be married, and Jean-Pierre has enrolled at Dr. Hunt’s university as a feminist studies major, becoming in the process the ideal companion for Hunt.