A series of diamond robberies have taken place all over the world. When Malynera's reserves are also emptied, Patalliro and Bancoran head to Japan following a clue in the form of a mechanical spider found on the scene.

However, while they're interrogating a suspect, he's assassinated before they manage to get any more information from him than the name of an organization, "Tarantella". Furthermore, the assassin seems to be Bancoran's former lover Bjorn, who's supposed to be dead! Is he really alive and involved in the case? Can our heroes find out more about him and the mysterious organization in time to put a stop to their plans?