The Griswold family, father Clark W., wife Ellen, daughter Audrey and son Rusty, set out in high spirit to spend their vacation driving cross-country from Chicago to a glorious climax in Walley World on the West Coast. The trip which Clark planned down to the minute, slowly loses its smoothness from the moment the first grain of sand gets in. A meeting with constantly-in-debt, simple-minded cousin Eddie results in the Griswold family giving cantankerous aunt Edna a lift to Phoenix. Of course, the Griswolds receive one strike of bad luck after another, and when they finally arrive at Walley World, they have to find out that the park is closed for maintenance. But Clark promised his beloved family the best vacation ever...