In 1889, the vicious Queen of the South Sea collects men that she murders during sex, thanks to a magical eel that lives inside of her vagina and bites the penises off of those who can't satisfy her lust. Finally, one man pleasures her long enough to reach inside and pull out the creature, which instantly turns into a dagger.
Furious, the Queen vows that she'll take her revenge on the man's great-granddaughter, and goes into the sea to wait for one hundred years. A century passes, and Tania, a plucky anthropologist, finds an ancient book on the legend of the Queen and decides to investigate.
She charters a boat to take her to the area where the Queen is believed to have disappeared, but while skindiving, a tidal wave destroys the vessel and Tania suddenly finds herself tied to a bed in a mysterious room. When a mystical eel enters her, she is possessed by the spirit of the bloodthirsty Queen.
After killing a pair of drunken punks in a lascivious manner, she sees the image of Erika, a pop singer, on television and recognizes her as the descendant of the man the Queen vowed revenge on a century before.
Armed with machine guns and impervious to bullets, the female assassin starts cutting a bloody swath through the city in an attempt to murder Erika, taking out scores of innocent bystanders, policemen and soldiers on her way. Erika's only hope is to recover the magic dagger that her great-grandfather has bequeathed to her for just this sort of emergency.