As the holidays approach, Clark Griswold (Chevy Chase) wants to have a perfect family Christmas, so he pesters his wife, Ellen (Beverly D’Angelo), and children, as he tries to make sure everything is in line, including the tree and house decorations. However, things go awry quickly. His hick cousin, Eddie (Randy Quaid), and his family show up unplanned and start living in their camper on the Griswold property. Even worse, Clark’s employers renege on the holiday bonus he needs.
A gadget salesman is looking for a special gift for his son and finds one at a store in Chinatown. The shopkeeper is reluctant to sell him the “mogwai” but sells it to him with the warning to never expose him to bright light, water, or to feed him after midnight. All of this happens and the result is a gang of gremlins that decide to tear up the town on Christmas Eve.