It was the dawn of man, and one tribe overslept! A small tribe of cave men lives peacefully in the woods of North America, spending most of their time in an endless search for food, the order of their lives established by their autocratic high priest. Their peaceful existence is shattered by an abundance of miracles from the sky -- a passing jet plane has jettisoned the passengers' luggage. Yuk, the cave painter, violates tribal customs and stares at the strange sight, earning banishment for himself and his friend Tull. The intrepid pair discover the wonders of modern civilization -- bowling balls, plastic fruit, sport jackets, etc. Excitement comes when two hoodlums track down their luggage (with their contraband inside). The bad guys are eventually foiled, but Yuk, Tull, and the beautiful cavegirl Hubba, leave for the modern world.