A scientist 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 when he accidentally brings a giant dinosaur back into Los Angeles.

In the prehistoric past, D'Leh is a mammoth hunter who bonds with the beautiful Evolet. When warriors on horseback capture Evolet and the tribesmen, D'Leh must embark on an odyssey to save his true love.