The movie stars identical twins actors Cole and Dylan Sprouse, who play Justin, a eight year old boy who thinks he sees his mother kissing Santa Claus. However "Santa" is actually Justin's father. Overhearing his parents Stephanie and David Carver having a heated argument, young Justin Carver retreats to his bedroom. A few minutes later, Justin peeks downstairs, only to see his mother Stephanie locked in a warm, romantic embrace with none other than "Santa Claus". Fueled by his best friend's worries over his recently separated parents, Justin jumps to the conclusion that his mother is having an affair with Santa. So, Justin decides to behave as badly as possible in an attempt to prevent Santa coming to his house on Christmas Eve night lest he make off with the boy's mother. The resulting hi-jinks include Justin setting traps and throwing snowballs at a street Santa.