A group of female freedom-fighters led by Karine Levere is caught by the warden of a women's prison, located somwhere in the South American jungle. None of them will reveal the secrets of their organisation or the names of their collaborators in the cities, so they are handed over to Dr. Costa who, after four years inactivity in Europe, is delighted to be able to practice his torture techniques once more. Laverne fails to resist the inhuman treatments and reveals all. The only hope of saving the organization is for the girls to warn the city cell before it's too late. They trick the prison guard into having sex with them, knock him out and break out of prison. The warden and Dr. Costa must prevent them from revealing the practices inside the prison. The hunt is on and it's shoot to kill...

15岁的少女玛丽·罗沙里亚（苏珊·海明威 Susan Hemingway 饰）因与未婚夫克里斯多巴尔在郊外嬉戏，而被目睹于此文森特神父（威廉姆·伯格 William Berger 饰）指责为淫荡与不贞。在文森特的恐吓下，玛丽的母亲（Patricia Da Silva 饰）被迫献出积蓄并将女儿送入瑟拉德阿里斯修道院。这座修道院表面看起来严禁虔诚，玛丽进入这里不仅要检查其贞操，还要讲述自己的罪行，并持续三天苦行与祷告。然而所谓的虔诚似乎只是幻象，背地里修女们拜祭魔鬼撒旦（赫伯特·福克斯 Herbert Fux 饰），举行邪恶而狂放的仪式。
玛丽企图逃跑，却被告密而面临严厉的审判。肉体与精神遭受痛苦的折磨，玛丽只得写信给至高的上帝……