A Carcaroth has arrived on Earth, seeking soldiers to help fight his endless intergalactic war back home. Using Combat 3000 to sift out the best, most aggressive and instinctive fighters, he then transports them to his spaceship – awaiting transfer to the war. Clyde (David Anthony) and Luke (Tommy Knight) find themselves amongst the 'warriors', while Sarah Jane (Elisabeth Sladen) and Maria (Yasmine Paige) must infiltrate the alien's headquarters to bring down the Carcaroth from the inside.