Dateline - the day after tomorrow. When a mysterious extraplanetary signal is detected emanating from Mars, the world security organisation known as Spectrum sends agents Captain Scarlet and Captain Black to investigate. Reaching the red planet, the two men leave their ship and head for the surface in their Bison Alien Terrain Vehicle, where they soon discover the source of the signals; a huge alien city, which materialises before them. The aliens dispatch a probe to examine the Earth vehicle, but Black assumes it to be hostile, and fires a burst of missiles which destroys the entire city. However, the alien buildings immediately reform, and the citys inhabitants, the Mysterons, retaliate by killing Black and declaring war on Earth. Scarlet manages to return to Earth with Blacks body, whic