When an unannounced uninvited and unwelcome family of fun-loving misfits converge upon a lakeside resort to join their relatives for a summer of relaxation the result is anything but restful. It's a vacationer's worst nightmare as wheeler-dealer Aykroyd his sexually repressed wife and eerie twin daughters 'join' the easygoing Candy and his straight-laced clan for a season of 'fun' in the sun. Unfortunately the only thing these two in-laws have in common is their intense dislike for each other. Soon it's brother-in-law against brother-in-law in an uproarious and hilarious fight to the finish to see which one really knows how to enjoy 'The Great Outdoors'.