Mean and domineering Jane and the sweet and ditsy Jackie are two radically contrasting sisters who suffer from severe trauma after witnessing the murder/suicide of their parents as well as seeing their other sibling Janice raped and killed by her assailants. The pair are deemed fit to re-enter society and get released from a sanitarium where they have undergone extensive rehabilitation therapy. However, Jane and Jackie prove to be anything but sane and harmless as they embark on a vicious spree in which they torture, murder, and mutilate any man luckless enough to cross their lethal paths.

Lucinda Regis, Director of Development at MALCO Oceanic Research, becomes the target of a dangerous killer after unraveling a sinister plot to inject sharks with human DNA.