
Once again, Gerry and Sylvia Anderson, the people behind The Thunderbirds, struck gold with their use of "Supermarionation," plastic puppets operated by very fine wires. Equipped with an electronic brain, the puppets’ eyes could slide sideways and blink, while their lips could move in sync with a prerecorded soundtrack. For a final touch of “realism,” photographs of real eyes were affixed to the puppets’ faces.
The puppets on Captain Scarlet and the Mysterons comprised a friendly crew of Earthlings, known as Spectrum, who had inadvertently caused an interstellar war when they were mistaken by inhabitants of Mars as an army bent on planetary invasion. The residents of Mars, energy beings known as Mysterons, swore revenge on the innocent Spectrum. They set out to capture and kill Captains Scarlet and Black, who were the top agents of Spectrum, and then bring them back to life to fight for the Martian cause.
The Martians had succeeded with Capt. Black, making him the main villain, but Capt. Scarlet was able to fend off the evil Mysterons and continue to use his immortal abilities for the Spectrum.
Each Spectrum agent had his own specific color and assignment: Col. White was the commander-in-chief, Capt. Blue was Scarlet's usual partner, Captain Grey acted as security, and Captain Ochre had worked previously with the World Government Police Corps. Captain Magenta was an Irishman, who seemed to serve no purpose other than comic relief.
But Spectrum was an equal opportunity employer and there were also five female agents, known as the Angels. Each one—Melody, Harmony, Rhapsody, Symphony and Destiny—was not only beautiful, but also a skilled pilot.
Airing in syndication in the U.S., Captain Scarlet and the Mysterons was one of the last Anderson shows to come across the Atlantic.