 Thanks to the money brought in at work by one of Clark Griswold s inventions, a long life food preservative, Clark has enough money to take his wife Ellen, his son Rusty, and his daughter Audrey on a trip to Las Vegas -- the land of sand, slot machines, and the Hoover Dam. In Las Vegas, Clark crosses paths with Eddie, the sloppy husband of Ellen s cousin Catherine. Eddie and his family now live in the desert north of Las Vegas on what used to be an H-bomb test site. During the vacation in Las Vegas, Ellen becomes addicted to Wayne Newton, Rusty gets a fake ID and becomes a winning high roller, Audrey starts hanging out with Eddie s stripper daughter Vickie, and Clark becomes addicted to gambling and starts gambling away the family s bank account, which amounts to $22,600. Ellen s obsession with Wayne Newton is making Clark jealous, and Clark keeps losing money at the casino. After losing so much money, can Clark find a way to get the money back and save the family s vacation?