Clark Griswold has invented a long-life food preservative, earning him a large bonus check. He announces to his family that he is taking them on vacation. Part of the reason for the trip is for Clark and Ellen to renew their wedding vows. Excitement wanes, however, when Clark says they are headed to Las Vegas. His wife, Ellen, and teenage daughter, Audrey, have their doubts, as Las Vegas is not known for its family-friendly atmosphere, while teenage son Rusty appears to be more enthusiastic.