Petey and Jean love to draw monsters. They create Oko, a frightening monster who escapes from the sheet of paper and disappears into their house. All they need to do now is create a nice monster that eats bad ones. So they draw a nice monster named Kriss with three legs, four arms and ten mouths to eat the bad monster. The plan works and they decide to keep Kriss as the family's new pet monster. For Christmas, Jean & Peter go on vacation to the mountains with their parents. Kriss was supposed to stay at home but he manages to make the trip on the roof of the car.