A scientist friend of Champignac, Professor Inovskyev, hides in his castle as he has just invented the GAG. This device has many purposes including making snow fall, making plants grow instantaneously and in gigantic proportions, making persons and objects levitate, etc. It's for these reasons coveted by men in black, who already kidnapped Pr. Longplaying, Inovskyev's coworker. Longplaying is the only other person who knows how to do a GAG, and is consequently held prisoner in a giant Buddha statue. It's up to Spirou and Fantasio to free him.
Tropes associated with this story include
- Security Cling: Spirou jump in Fantasio's arms when a giant acorn nearly fall on him.
