Last House on the Left is a powerful film to say the least, but what many people do not realise is that the film bears a close relationship to the films "The Virgin Spring" by Ingmar Bergman. Last House on the Left takes the forest setting and story of rape and revenge from The Virgin Spring and transports them into a modern tale of crime, drugs and rape.

On her seventeenth birthday, Mari Collingwood and her friend Phyllis drive into town for a rock concert. Escaped sex murderers Krug and Weasel have meanwhile taken refuge in town with Krug's girl Sadie and addict son Junior.

When Phyllis tries to buy marijuana from Junior, he lures the two girls back to the gang's hideout, where Phyllis is beaten and raped.

Next day, the gang bundle the girls into the boot of their Cadillac and set out for the Canadian border. Near the Collingwood house, the car breaks down, and Phyllis tries to escape.

She is cornered in a churchyard by Krug, Weasel and Sadie and stabbed to death. Mari talks Junior into letting her go (promising her a fix from her doctor father's medicine cabinet), but she is mutilated, raped and finally shot by Krug.

The gang chance upon Mari's house and are taken in by Dr. and Mrs.Collingwood. But the Collingwoods find the barely alive Mari, and are told of the gang's guilt.

Dr.Collingwood plans revenge. Mrs.Collingwood seduces Weasel and castrates him during fellatio. Dr.Collingwood leads Krug into several homemade traps, but the psychopath defeats him in a fist fight.

Junior intercedes for the doctor's life and is forced by his father to commit suicide. Mrs.Collingwood chases Sadie into the swimming pool and cuts her throat. Dr.Collingwood manages to kill Krug with a chain saw. The police finally arrive.