 Chicago resident Clark Wilhelm Griswold Jr has REALLY got the Christmas spirit this year, and his wife Ellen, son Rusty, and daughter Audrey have noticed it. Clark has invited Ellen s parents Arthur Smith and Francis Smith, his own parents Clark Wilhelm Griswold Sr and Nora Griswold, and his Aunt Bethany and Uncle Lewis to spend the holidays at the Griswold house in Chicago. Clark is obsessed with making everything go perfectly during the holiday season, but as soon as everyone arrives, things start going haywire, especially when the Griswolds receive some uninvited surprise guests from Kansas -- cousin Catherine, her sloppy husband Eddie, and two of their kids, Rocky and Ruby Sue. Clark decorates the outside of the house with 250 strands of lights with 100 bulbs on each strand for a total of 25,000 light bulbs, enough to make the power company turn on their auxiliary nuclear generator. Clark also annoys his snobby next door neighbors -- Todd Chester and his wife Margo. Even with his bumbling ways, Clark manages to keep things going as he waits for his Christmas bonus from work so he ll have enough money to have a swimming pool put in the back yard. But it turns out that Clark s boss, a scrooge whose name is Frank Shirley, does not intend to give out any Christmas bonuses this year, and this causes Clark to snap and act crazy. This situation gives Eddie the idea for the perfect Christmas gift for Clark after Clark offers to help Eddie treat Rocky and Ruby Sue to a good Christmas. Can Eddie help Clark and the family have a great Christmas?