Concluding from where "Crater 101" left off, Spectrum take a chance by commencing a maximum security operation to bodyguard radio communications expert, Doctor Kurnitz from the Nash Institute of Technologies, up to Cloudbase to send a broadcasted voice message by Colonel White to the Mysterons base on Mars, in an effort to solve their differences and to end the raging war of nerves between them.
But the Mysteron pulsator stolen by Captain Scarlet during the expedition to Crater 101 is used as an explosive charge to start a chain reaction on-board Cloudbase which will no doubt utterly destroy the aerial base. With Scarlet drawn away by Captain Black to prevent him from saving his fellow officers, the world-security organisation known as Spectrum is condemned to be crippled.