The Mysterons are non-corporeal beings, although they once possessed bodies (The Achilles Messenger). They live in a city on Mars that is normally hidden from view. The city appeared on the surface of Mars for the first time in 2068, during the ill-fated mission commanded by Captain Black (Instrument of Destruction part 1).
The Mysterons claim to be peaceful beings, but are currently waging a war of nerves against the people of Earth following Captain Black's unfortunate actions that resulted in the total destruction of the Mysteron city.
The Mysterons possess the ability to reconstruct exact replicas of objects or persons. It is due to this remarkable ability that they were able to recreate their city following Black's attack. They also employ this power from time to time during the 'Mysteronisation' process, which renders the reconstruct (dubbed 'replicant' by Spectrum) with the power of retrometabolisation - the replicant is able to heal completely from almost any injury, including fatal ones. The only known survivor of the process is Captain Scarlet, who retains his retrometabolism and is virtually indestructible (Doctor Gold, Instrument of Destruction part 1), an ability which is a great asset in his work. However, retrometabolism is not always present in replicants, as in the case of Astrid Winters, (The Achilles Messenger).
Mysterons are also able to control the minds of their human victims, whether the subject has been replicated or not. Mysterons make use of hypnosis for short-term control, as demonstrated by the replicant of Commander Lewis on Doctor Gold (The Homecoming). For more lasting agents, they use the reconstruction process which leaves them in total control of the body.
The Mysteronisation process alters the replicants at the sub-atomic level and subtly alters their genetic code. It is this alteration of DNA that leaves them vulnerable to detection, and all Spectrum personnel are subject to DNA checks on a regular basis. There is no known test that can be performed in the field at this time.
