Pursued by warmongering beast-like Rulons, peaceful Valorians fly through a wormhole and end up on prehistoric Earth. Rulons follow and become stuck there as well. Valorians tame the dinos and settle in, while Rulons build a dino army.
Using the STEP Time Crystal, the Valorians crash land on prehistoric Earth, followed by the evil Krulos and the Rulons. Krulos must defead the Valorians and recapture the crystal before his forces can return to his time.