Orphaned by a plane crash, raised in the wilds of a lost world hidden somewhere beneath a constant mist, The Big Guy and his ape-man brother from another mother are living a life of danger amongst rampaging dinosaurs, giant birds, warring ape tribes, and all manner of deadly beasts. It's a wonderful existence for someone like The Big Guy and his furry brother, except for the flea problem. Then an expedition of explorers from the outside turn his world...