The year 2011 AD. The war between the Angel Squadrons and the Gofer Sisters has ended, but the music box from that era has been formally banned. The Inter-Dimensional Organization G now confronts a new Bacterian Army, and four new member squadrons are assembled to face the unknown Bacterian Force. A dark power has reached Earth with plans to destroy it, and the only counter is to travel back in time and confront the Bacterian threat at its most dangerous point on the surface of Planet Gradius.