Forensic psychologist and detective Alex Cross travels to North Carolina and teams with escaped kidnap victim Kate McTiernan to hunt down "Casanova," a serial killer who abducts strong-willed women and forces them to submit to his demands. The trail leads to Los Angeles, where the duo discovers that the psychopath may not be working alone.

A team of scientists working on a remote dig site find the buried body of an enormous monster, perfectly preserved even after 200 million years. As soon as the beast is uncovered, however, an alien spacecraft suddenly appears above them and brings the monster back to life! The creature immediately sets about levelling the surrounding urban landscape and shrugging off the best firepower the military can throw at it. A lone scientist, working on decrypting an ancient set of hieroglyphics, may be on the verge of finding the aliens' weak point, but will it be too late?