Ruth has a hobby of kidnapping young women and taking them to her secret cabin in the woods so that she can torture them to death. To help her get away with these crimes, she has random one-night stands with men and collects their sperm, which she then places into the orifices of her corpses.
One morning, a young door-to-door saleswoman named Geraldine comes to Ruth's home selling vacuum cleaners. Quickly finding herself unable to control her sadistic excitement, Ruth incapacitates Geraldine and brings her to the secluded spot. There, she uses a corrosive acid to destroy the woman's vocal chords and then proceeds to abuse her.
Later that night, while Ruth is sleeping, Geraldine manages to free herself, but before she is able to escape the cabin, she is captured by three delinquent alien fugitives who are on the lam after robbing a bank on their home planet, Seotrool. The Seotroolians locate and bind Ruth as well, and demand that she tell them how to operate the "strange vehicle" (Ruth's car) that sits outside. Ruth, however, fearing that she will be killed after providing this information, refuses to tell them. The aliens then turn to Geraldine, but since she is unable to speak, she is of no help either.
It is here that Ruth gets an idea. She pretends that she is Geraldine's older sister, and that she cares for her well being more than anything in the world. The ruse works, and immediately provokes the aliens to torture Geraldine until "her sibling" talks. Initially, they have no clue that Ruth, is in fact, sadistically enjoying the show, but this soon changes. Furious at being deceived, the aliens drag Ruth outside to that she will show them herself, but waiting in the front of the cabin is the Seotroolian police, who ends up shooting two of the fugitives dead, and arresting the third. The aliens leave earth, but accidentally leave behind one of their weapons. Excited, Ruth rushes back into the cabin with the intent of testing the weapon out on Geraldine, but discovers that her victim has already perished.
The story implies that a sequel would be made one day, but one was never released.