Plot
The movie is set in the mid 22nd century. The planet Mars has been terraformed, allowing Humans to walk on the surface without having to wear pressure suits. The story concerns a police officer, Melanie Ballard (Natasha Henstridge) who is leading a small team to pick up and transport a prisoner named Desolation Williams (Ice Cube). Arriving at the remote mining town where Williams is being held, Ballard finds virtually all of the people missing. On investigating she discovers that the miners found an underground doorway which had been created by an ancient Martian civilization. When the door was opened it released the titular "ghosts", disembodied spirits who possessed the miners. The Martians were apparently a brutal people dedicated to acts of random violence and the practice of self mutilation. The self mutilation however may be merely the alien spirits attempting to alter their human bodies to look more like those of the aliens themselves (which are only partially seen very briefly).Ballard must fight off the attacking miners, escape the town, and if possible destroy the ghosts. Unfortunately all these tasks are complicated by the fact that killing a possessed human merely releases the Martian spirit, which immediately possesses another human.
Trivia
*Although mars has a day/night cycle almost identical in length to Earth's, most of the movie is set at night. The only moment in which we see Mars during the daytime is in a flashback through the character of the scientist, when she talks about how she found and opened "Pandora's Box" that let the alien spirits out.*Much of the movie was filmed in a gypsum mine in New Mexico. The pure white gypsum had to be dyed with thousands of gallons of biodegradable red food dye to recreate the appearance of the Martian landscape.
