The action begins in Tibet, where the megalomaniac Emperor Basam Damdu wants to provoke the Third World War. He is assisted by an unscrupulous adventurer who calls himself Colonel Olrik. While preparations are going well, Blake and Mortimer are developing the only weapon that can still save the free world. The assault launched, our heroes must take the plans to a secret submarine base of the Indian Ocean. But many peripets will hinder them in their march towards the meeting point. Volume 2 tells how, after losing the plans of the famous Espadon, Mortimer is captured by wanting to recover them, then his escape from Olrik's hands. Finally, the last volume describes the latest preparations for the counterattack whose point of departure lies from the secret base allied. Olrik, infiltrated within it, will attempt to make everything fail but without success. The adventure is concluded by the triumphal march of the invincible Espadon, thus restoring to the world his freedom.