In the African desert, Spectrum is assisting Professor Susan Todd of Hydra Laboratories with a revolutionary irrigation scheme, seeding the atmosphere with a hygroscopic compound to generate rain. Scarlet joins Todd for the initial experiment, sharing her excitement as the project proves to a complete success and she is caught in a torrential downpour. Back on Skybase, they celebrate with Colonel White and Hydra director Vandamm but Todd suddenly become paranoid and irrational, pulling a gun on Vandamm and taking him hostage. As the situation spirals out of control, the Colonel begins to suspect that the Mysterons have done something to the rain...