On Mars, the viability of the final stages of Operation Exodus is debated, with the Martian military preferring a plan to use a Plasma cannon based on ancient Solnoid technology to destroy the MME citadel and end the war in one strike. The displaced earth resistance members of Operation Exodus and their allies in the Mars military disobey orders and take a ship to earth. On earth, GORN, the leader of the MME, captures Sandy Newman in order to obtain access to Earth's orbital weapons, which it plans to use to prevent the Martian assault. Sandy Newman and GORN must work together to prevent the Mars forces from destroying the earth's chance of survival.