Dawn Davenport, a delinquent high-school student, goes berserk when her parents refuse to buy her the shoes she wants for Christmas because “nice girls don’t wear cha-cha heels”: she destroys presents, topples a Christmas tree on her mother, and flees the house. Dawn hitchhikes a ride with a lecherous man, Earl Peterson, who drives her to a dump where they have sex on a discarded mattress. Dawn becomes pregnant, but Earl refuses to support her. She gives birth to a daughter, Taffy, a brattish child often beaten and severely punished by her mother. Dawn works various jobs, including stripping and waiting tables, and engages in criminal activities such as burglary and street prostitution with former high-school friends Chiclette and Concetta.
Dawn begins frequenting the Lipstick Beauty Salon and marries Gater Nelson, her hair stylist and next-door neighbor. Donald and Donna Dasher, the fascist owners of the beauty salon, recruit Dawn in a scheme to prove “crime and beauty are the same”. They entice Dawn to commit crimes by promising her fame, supplying her with drugs and money, and photographing her crimes to stoke her vanity.
Gater’s aunt, Ida Nelson, is distraught over her nephew’s marriage because she hopes he will “turn nelly” and take a male lover. When the marriage fails, Dawn persuades the Dashers to fire Gater, who moves to Detroit to work in the auto industry. Ida blames Dawn for driving Gater away and exacts revenge by throwing acid in her face, leaving Dawn hideously disfigured. The Dashers discourage Dawn from having corrective cosmetic surgery and use her as a grotesquely made-up model. They kidnap Ida, imprison her in a large birdcage in Dawn’s apartment, and give Dawn an axe to chop off her hand as revenge for the acid attack.
Taffy, now a teenager, is distressed by her mother’s criminal lifestyle and convinces her to reveal the identity of her father. Taffy finds her father living in squalor and drinking excessively. She stabs him to death with a chef’s knife after he tries to sexually assault her. Taffy returns home, falsely claims she was unable to locate her father, and announces she is joining the Hare Krishna movement. Dawn warns her she will kill her if she does.
Dawn, now with bizarre hair, make-up, and outfits provided by the Dashers, mounts a nightclub act. When Taffy appears backstage chanting mantras in religious attire, Dawn fulfills her threat and strangles her to death. Dawn brandishes a gun onstage during her nightclub act and begins firing into the crowd, wounding and killing several audience members. When police arrive to ostensibly subdue the crowd, they shoot several audience members themselves. However, they allow the Dashers to leave when they claim to be upright citizens caught in a bloody rampage. Dawn flees into a forest, but is soon arrested by the police and put on trial for murder.
At the trial, the judge grants the Dashers immunity from prosecution for testifying against Dawn. The Dashers feign innocence and completely blame Dawn for the crimes she committed at their behest; they also pay Ida to lie on the witness stand. Although Dawn pleads not guilty by reason of insanity, the jury finds her guilty and sentences her to die in the electric chair. As a priest says a prayer and Dawn is strapped to the electric chair, she thanks her fans for her notoriety before being electrocuted.