L'Affaire Tournesol
In "Destination Moon", the Sprodj Atomic Research Centre invites Professor Calculus to head its space division, and later Tintin and Captain Haddock to be part of the Moon mission. In "The Calculus Affair", Syldavia's secret agents compete with archrival Bordurian agents to kidnap Professor Calculus and obtain the secrets to develop sound-based weapons.