Scarlet (Francis Matthews) is an American working for Spectrum who had been killed by the Mysterons and replaced with a "reconstruction", or doppleganger. When said double was also killed, it was brought back to life with the original's memories, freeing him from Mysteron control.
Producer Reg Hill would later work on the live-action Space: 1999. Ed Bishop, later of UFO, was heard as Captain Blue.
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