Wow. I haven't thought about Captain Scarlett in years. I remember watching it when i was VERY little and being scared by those two white circles of light (the Mysterons!) The song still echoes in my head..... Thanks Jack!
The first Earth expedition to Mars discovered the Mysterons, who were as curious about the universe as we were. When they pointed their cameras at the expedition to get a closer look, the leader, Captain Black, mistook them for guns and fired. The Mysterons, understandably ticked off (though maybe overreacting a bit, since they could recreate anything) declared a terrorist war. Captain Black was possessed by one of them, becoming the main bad guy. Captain Scarlet was another early rouge agent who's life, mind (soul?), was restored by the end of the first episode, making him Spectrum's number one agent.