A scientist from the failed Philadelphia Experiment leads a team of Navy SEALs back in time to the Cretaceous Period to rescue the first team he sent back during the 1940s. Things go wildly awry though, when on his return he accidentally brings a giant, man-eating dinosaur back through the portal and into modern-day, downtown Los Angeles.

As the Earth wrestles with its agonizing birth, the peoples of this barren and desolate world struggle to survive. Driven by animal instinct they compete against the harsh conditions, their giant predators, and warring tribes. When two people from opposing clans fall in love, existing conventions are shattered forever as each tribe struggles for supremacy and Man embarks on his tortuous voyage of civilization.