Spirou, Fantasio, the Count of Champignac and some other scientists from all over the world are invited to the isolated estate of the stay-at-home millionaire Thorpe. Thorpe is working on the production of ecofriendly energy. His friend Basile de Koch, a big industrialist, seems to be interested in this experiment. When some of the scientists disappear, everybody gets scared. Spirou discovers a tunnel system under the estate of Thorpe, which is the center of de Kochs espionage. In this tunnel-system, he keeps the other scientists and wants to render them harmless, because he wants to keep producing nuclear energy. One of the scientists, a Japanese named Sushiaky, is able to do the 'Yakaya' scream, which can paralyze any enemy.