In the Universal Century year 0079, the space colony known as Side 3 proclaims independence as the Principality of Zeon and declares war on the Earth Federation. One year later they are locked in a fierce battle for the Thunderbolt Sector, an area of space scarred by the wreckage of destroyed colonies.

The fleets of the Earth Federation's Moore Brotherhood and the Republic of Zeon have shattered each other in a bloody battle for the Thunderbolt Sector. Mirroring the greater struggle, the ferocious duel between Io Fleming and Daryl Lorenz leaves both the Full Armor Gundam and the Psycho Zaku heavily damaged and Io a prisoner of war. The Zeon space habitat A Baoa Qu now becomes the final battleground of the One Year War...