In a modern stone-age world, Barney's attempt to repay his friend Flint for helping him adopt a child by swapping their answers for an aptitude test backfires when Barney finds himself out of a job and Flint discovers that he was awarded his new position to take the fall for a scheme.
As Fred, Barney, Wilma and Betty embark on a recreational trip to Rock Vegas, things take an unexpected turn when a rich womanizer falls for Wilma.