It's Mars, 2176, and 640,000 people now live in various outposts on the red planet, working in several mining operations and nearing completion of making the air completely breathable. When a train arrives in the city of Chryse on autopilot with only one survivor and scores of bodies in its wake, a colonial council opens an investigation into what occurred.
Accordingly, police officer Lt. Melanie Ballard (NATASHA HENSTRIDGE) is questioned about how she became that sole survivor and she then recounts her tale. It seems that a police transfer team headed by Commander Helena Braddock (PAM GRIER) and consisting of Ballard, Jericho (JASON STATHAM), Bashira (CLEA DUVALL) and Descanso (LIAM WHITE), arrived in the mining town of Shining Station to transport a prisoner, James "Desolation" Williams (ICE CUBE), back to Chryse.
Upon arriving in the town, however, the team discovers the prisoners still locked up, but all of the guards missing and/or dead. They soon learn from one of the few sane survivors, Professor Whitlock (JOANNA CASSIDY), that most all of the colonists have been possessed by an unleashed, ancient Mars spirit and have gone mad, forming angry mobs that follow a crazed leader and kill anyone who doesn't fit in with them.
As they then battle the crazed and homicidal colonists and deal with Williams and a trio of criminals -- Uno (DUANE DAVIS), Dos (LOBO SEBASTIAN) and Tres (RODNEY GRANT) - who've arrived to spring him from jail, Ballard and the others do what they can to survive and get themselves out of the town before the hordes overtake and kill them.