Set in 2068, Captain Scarlet presents the hostilities between Earth and a race of aliens known as the Mysterons. After human astronauts attack their city on Mars, the vengeful Mysterons declare war on Earth, initiating a series of reprisals that are countered by Spectrum, a worldwide security organisation. Spectrum boasts the extraordinary abilities of its primary agent, Captain Scarlet. During the events of the first episode, Scarlet acquires the Mysteron healing power of "retro-metabolism" and is thereafter considered to be virtually "indestructible", being able to recover fully from injuries that would normally be fatal.