Written by the Andersons and directed by Desmond Saunders, it was first officially broadcast on 29 September 1967 on ATV Midlands, although it had received an unscheduled test screening in the London area five months earlier.
[4] Set in 2068, the series depicts a "war of nerves" between Earth and the Mysterons: a hostile race of Martians with the ability to create functioning copies of destroyed people or objects and use these reconstructions to carry out specific acts of aggression against humanity.
Earth is defended by a military organisation called Spectrum, whose top agent, Captain Scarlet, was murdered by the Mysterons and replaced with a reconstruction that later broke free of their control.
The double of Scarlet has powers of self-repair that enable him to recover from injuries that would be fatal to any other person, which make him Spectrum's best asset in its fight against the Mysterons.
In 2068, the crew of the Zero-X spacecraft are investigating the surface of Mars in their lander, the Martian Exploration Vehicle (MEV), to locate the source of unidentified radio signals detected by the Spectrum security organisation on Earth.
The astronauts mistake the Mysterons' surveillance devices for gun batteries, and the mission leader, Spectrum officer Captain Black, orders his men to fire on the city with the MEV's rocket launcher.
Unaware that the original Scarlet is dead, White orders his double to fly the President in a Spectrum Passenger Jet to a second Maximum Security Building in London.
However, when Brown's body is discovered at the scene of the car crash, White realises that the President is in the hands of an impostor and orders Scarlet to return to Cloudbase.
Arriving at a garage, Captain Blue exchanges his patrol car for a Spectrum Pursuit Vehicle (SPV) and begins to follow Scarlet.
White suggests that Scarlet's powers of self-repair make him virtually "indestructible" and that he is destined to become Spectrum's greatest asset against the Mysterons.
"The Mysterons" was written by the husband-and-wife team of Gerry and Sylvia Anderson, assisted by series script editor Tony Barwick.
[7][14] Other differences included a longer Cloudbase introduction, in which the Angels are launched but subsequent dialogue reveals that this is a drill (in the finished episode, only the launch is shown); an additional scene in which Symphony and Melody Angels watch from the Cloudbase promenade deck as the Spectrum jet takes off; Captain Blue converting the SPV's removable power unit into a personal rotorcraft, or "minicopter", to take on Scarlet (in the finished episode, he wears a jet pack instead); and an additional line of dialogue stating that the original Helicopter A42 crashed half an hour before its reconstruction attacked Blue.
[19] Although the puppet was modelled on McGoohan, the actor was unable to commit to the role, and the guest star idea was later abandoned due to budget constraints.
[8][9] As special effects supervisor Derek Meddings was busy working on Thunderbird 6, his designs for "The Mysterons" were limited to the Spectrum vehicles that he expected to appear in more than one episode: Cloudbase, the Angel Interceptors and the SPV.
[30][31] According to Meddings: "We spent hours furnishing miniature rooms – actually plastic tool box drawers – but when we eventually set off the explosives they created so much dust that we couldn't see a thing, so our efforts were completely wasted.
A scene in which Captain Brown and the President are scanned for concealed weapons while travelling down a moving walkway was especially difficult to film as the puppet operators on the bridge above the set had to synchronise their movements with the conveyor belt beneath them.
[34] The incidental music was performed by a 16-member band and recorded by series composer Barry Gray during a four-hour studio session held on 16 March 1967.
[40][41] In January 2008, the episode was screened as part of a Gerry Anderson-themed night of programming on BBC Four, when it was seen by 0.35 million (an audience share of 1.54 per cent).
[42] As originally edited, the episode shows the MEV crew firing on the Mysteron city only after they mistake the movements of the aliens' surveillance towers as preparations for an attack.
[12][13] In a preview of the episode's first BBC showing, James Rampton of The Independent wrote: "The best thing about the programme is that it's just as ludicrous as you remembered: the lips bizarrely out of sync with the words, the strange uniformity of features [...] and the totally preposterous dialogue ('Despite his fatal injuries, he's returning to life').
"[12] In a review for the same newspaper, Allison Pearson was comically critical of certain design aspects, such as the surface of Mars, the exterior of the Mysteron city and the model of the Car-Vu (which she likened to a "Philippe Starck cake-stand").
[14] Paul Cornell, Martin Day and Keith Topping, authors of The Guinness Book of Classic British TV, highlight Brown's conversion into a living bomb as an example of the sometimes "incredibly violent" tone of the series.
[15] Andrew Blair of website Den of Geek calls the explosion of Brown "quite an unnerving thing to watch" but regards the episode in general as "tailor-made to appeal to small boys and men-children".
[16] Although the Mysterons ultimately fail to kill the World President, Gary Russell of What DVD magazine points out that their attempts on the target's life result in considerable collateral damage: "[Spectrum] lose three Captains (Scarlet, Brown and Black), a helicopter, a pursuit vehicle and a saloon car.
In an interview, Gerry Anderson described this version of the first contact between humanity and the Mysterons as "ten thousand times better than the original – much more exciting, much more real.