In the Stone Age story line, Keaton competes with the bigger, brutish Beery for a cavewoman, Leahy. After observing another caveman drag away a woman by the hair in order to "claim" her, Keaton tries to become more assertive. But he is continuously pushed back and bullied by Beery. An attempt to make Leahy jealous by flirting with another woman ends in failure. Nevertheless, Keaton grows closer to Leahy, and Beery challenges him to a fight at sunrise. Keaton wins thanks to hiding a rock in his club, but is caught and tied to the tail of an elephant to be dragged around the dirt as punishment. Upon his return, he finds Leahy about to be claimed by Beery and attempts to make off with her. Beery catches him and the two battle by tossing boulders at each other from afar, with Keaton and Leahy on a cliff together. When Beery climbs up to reclaim Leahy, Keaton dispatches Leahy's cronies and finally defeats him. He drags a smitten Leahy off by the hair. In the epilogue, they go off for a walk with their huge family of children following them.