Three weeks after losing contact with Elysium Base on Mars, a team consisting of Captains Scarlet and Blue, Destiny and Harmony Angels, and Doctor Gold are sent to find out what happened to the crew. On arrival, they realise it is a Mysteron trap and that they are under attack from an titanium armour-plated research robot named Remote Acquisition Technology (RAT) which carries lasers and a diamond-tipped saw. Under Mysteron control, the RAT has become the ultimate killing machine.