eighteen years ago, the prehistoric past collided with the present as time itself underwent a tremendous disruption, transporting huge swaths of the cretaceous period into the twentieth century. neighborhoods, towns, and cities were replaced by dense primeval jungles and modern humanity suddenly found itself sharing the world with fierce dinosaurs. in the end, desperate measures were taken to halt the disruptions and the crisis appeared to be over.
new dinosaurs begin to appear, rampaging through cities. a secret mission to the moon discovers a living tyrannosaurus rex trapped in an alternate timeline. as time begins to unravel once more, nick paulson, director of the office of security science, finds a time passage to the cretaceous period where humans, ripped from the comforts of the twenty-first century, are barely surviving in the past. led by a cultlike religious leader, these survivors are at war with another sentient species descended from dinosaurs.
as the asteroid that ends the reign of dinosaurs rushes toward earth, nick and his allies must survive a war between species and save the future as we know it.