Morbid by a red viper at the bottom of a real underground labyrinth while he had finally discovered the legendary rock in the thousand eyes of the goddess Skaedi, Thorgal must nevertheless manage to extract and bring back a fragment of this mysterious stone fallen from Asgard, if he wants to save Jolan and Boréale. The help of a young snake hunter will not be too much for our "child of the stars", if he wants to have a chance to triumph on Odin's chess board!