Shadow of Fear

Captains Scarlet and Blue travel to the Himalayas to supervise and administrate Spectrum's new phase to monitor signals from a space satellite that has been launched into the orbit surrounding Mars, and to snap-shot high resolution detailed pictures of the planet, which will be relayed and received by the large mountain satellite station that the probe was launched from.
The second satellite, with the first acting as a decoy, successfully lands on Mars, and sets to have Spectrum successfully completing the code-named "Project Sword" operation, but the whole carefully planned arrangement is placed under threat when one of the participating technicians ostensibly falls dead and is brought back to life by the Mysterons, with one instruction: to sabotage the observatory and to interrupt the satellites' transmission before Earth comes to learn every single detail about the force and prevent them from continuing the war of nerves and retaliation against the planet.