Melanie Ballard (Natasha Henstridge) is a hard nosed police chief in the year 2025. She and a police snatch squad are sent to Mars to apprehend a dangerous criminal James Williams (Ice Cube). Mars has been occupied by humans for some time and they have set up mining facilities. The mining activities on Mars have unleashed the spirits of alien beings who gradually possess the bodies of the workers. It soon turns out that catching the dangerous fugitive takes a back seat as the alien spirits begin to rid their planet of the ‘invaders’.
This time, a cataclysmic temblor hits Los Angeles, turning it into an island. The president views the quake as a sign from above, expels Los Angeles from the country and makes it a penal colony for those found guilty of moral crimes. When his daughter, part of a resistance movement, steals the control unit for a doomsday weapon, Snake again gets tapped to save the day.