Scott Calvin has been Santa Claus for the past eight years, and his elves consider him the best ever. But Santa's world is turned upside down when his son gets on the naughty list, and if Scott doesn't marry soon, he'll stop being Santa forever.

Deputy District Attorney Dave Douglas takes his job very seriously -- so seriously, that his wife and family hardly ever see him. A case involving an animal laboratory finds Dave once again taking an extended leave of absence from his frustrated family. His luck takes a turn for the worst after he is inadvertently infected by a top-secret genetic-mutation serum that transforms the two-legged lawyer into a four-legged sheepdog. Though his current situation...