In the year 2041, the rebel Centros are a plague to the survivors of the great toxic gas scare of 1993. A renegade Megarobot pilot and an archaeologist must team up (despite personal differences, a reluctant romance, and official pressure to cease and desist) to thwart the Centro's attempts to resurrect a hidden Megarobot, with which they can challenge the prevailing order.

The citizens of Comet Valley are being taken over by seeds from an alien plant that has taken root there. A sheriff investigates the strange goings-on.