A young Mexican nun, named Sister Sarah, is neglected and abused by a corrupt clergy that produces and distributes heroin. After a bad drug deal, she is handed over to thugs to be used as an instrument as sex for money. On the verge of death after being heavily drugged and wounded and fingered, the nun receives a commandment from God to take revenge. Acquiring heavy weapons (including big guns and vibrators), Sister Sarah sets out to kill those who had abused her and are using the church for their own personal gain. The frightened drug lords in the church hires "Los Muertos", a violent motorcycle gang, to track her down and eliminate her. Los Muertos' base of operations is the local brothel "Titty Flickers", where they to try and gather more information on the vigilante nun. After being wounded in a shootout, Sister Sarah hides out in a fleabag motel where she recovers and finally achieves vengeance by killing Los Muertos, degenitalizing Chavo (the brutal leader of Los Muertos), and saving her female lover who had been raped. But in the final scene, the clergy drug lord, known only as the Monsignor, hires another hit man to track down the vigilante nun, leaving the door wide open for a sequel.