In the Middle East a group of American soldiers are fighting the enemy and are attacked by these huge spider-like creatures that emerge, in a pack, from the rocky crevices. One of the smaller ones hitches a ride on a corpse and is shipped back to the States (does anyone remember ARACHNOPHOBIA?), where it escapes and starts reproducing in the desert and an alarming rate. Lots of people are gorily killed with lots of CGI bloodletting. There's also lots of generic characters we don't care about, including star Brian Krause (SLEEPWALKERS) and C. Thomas Howell (THE HITCHER, AMAZING SPIDERMAN).
The selling point for this movie is that this is based on "actual creatures that for years have tormented the United States armed forces in the Middle East". Yes, there are such real things as camel spiders, but they're not giant man-eating arachnids that are poisonous and grow incredibly fast and attack in packs. What the real "Camel Spiders" are are Solifugids, which are in the class Arachnida (as are scorpions and spiders). I used to have a six-inch one as a "pet" and it was one of the weirdest and ugliest things I've ever seen (and it has big jaws, so it can give a nasty bite!). Actually, the real-life creatures look much better than the ones in this movie, which simply resemble giant spiders, no different than any other giant spider movie.