Four teenagers and their faithful assistant, the extremely intelligent meerkat Nono, come to Norway to spend the Christmas holidays in the medieval castle of their grandfather, Dr. Abelmans. This extravagant old man once stood at the origins of cryptozoology - the science of cryptids, mysterious creatures that official science does not even want to hear about. At the same time, a tragedy occurs in Brittany - under mysterious circumstances, a fishing boat, controlled by the most experienced on the coast, is shipwrecked captain. The next day, in the Arctic Ocean, an oil tanker is attacked by a powerful unknown force... Secretly from everyone, the guys embark on a dangerous and exciting adventure that will lead them to the tracks of a terrible monster living in the depths of the sea. However, the secret services of many states are trying at all costs hush up the matter and prevent the guys from finding out the truth.