On its way back to Earth, the space shuttle Nautilus passes through a cloud of alien spores causing its sole occupant, astronaut Steve Thomas to transform into a blood-thirsty monster. The shuttle crashes into a swampy region of central Florida, creating a situation which threatens contagion and/or death to all who encounter the shuttle or its mutated pilot.

Diane is a repressed, neurotic grad student, who moves into a cursed mansion only to be possessed by the house's demonic master. She is then transformed into a raven-haired, leather and lingerie-clad seductress, who seeks a virgin sacrifice for her master. Meanwhile her sister, brother-in-law, a priest, and a pizza boy try to rescue her while avoiding the demon's wrath.

Someone is killing off the female leads of the movie production "Bad Girls from Mars." The producers feel they should try to finish the film, even though they're making a lucrative amount from insurance payoffs, so they fly in European sex bomb Emanuelle as the new lead. Emanuelle immediately begins embarrassing the producers by leading a wild party life around town. Meanwhile the killings continue, and detectives try to stop the fiend responsible.