Sixty-five million years ago... ... an artificial alien intelligence has come to strip-mine the prehistoric Earth - but when their robotic automations kill a mother T. rex, they start a war. One of her hatchlings has survived, traveling with an adoptive raptor pack - and as the orphaned tyrannosaur grows, they wage a guerrilla war against an invading army of war-bots and giant cloned-cyborgs. Primeval monsters battle alien machines as more prehistoric beasts join the fight, striking back against a common enemy. But the invaders also wield Doomsday weapons. One of them is the deadliest substance in the universe - a mutagen that can wipe out entire species. The other is a giant asteroid sent to destroy the world.