In the future, time travel is not only possible--it's a lucrative monopoly. It's especially profitable for Charles Hatton, the owner of Time Safari Inc., a travel agency that specializes in escorting wealthy clients on exclusive hunting trips back to the Prehistoric Age. Under the leadership of seasoned scout Dr. Travis Ryer, participants are permitted to hunt and kill dinosaurs--provided they follow a set of strenuous rules. These guidelines are intended to protect the creatures' natural habitats and prevent time travelers from impacting the course of evolution. When an expedition is compromised and the rules are broken, the hunters return to the future and discover the world is a markedly different place than it was when they left. As "time waves" ripple from the Prehistoric past through the present to the uncharted future, Ryer teams-up with Sonia Rand, the inventor of the time travel technology, to unravel the mystery behind the catastrophic historical changes that are now threatening to erase humanity from existence.