In late U.C. 0096. The Earth Federation government, regarding the existence of the "psycho-frame" as a threat, organizes the Mastema special forces team under the command of Lieutenant JG Mehmet Merca, a member of its intelligence bureau. The team is ordered to enter and investigate part of the shattered asteroid Axis, which is drifting in the Earth Sphere. The investigative team accompanying Mehmet includes two civilians named Arlette Almage and Danton Hyleg, who were formerly an engineer and a test pilot with the Principality of Zeon and Neo Zeon.
While investigating a supposedly unoccupied facility within Axis, Mastema comes under attack from a new model of Gundam that belongs to a private militia called Birnam. Arlette and Danton fight back using a red Zaku III Custom, a mobile suit they once helped develop. As the fighting escalates, Arlette, following a secret agenda of her own, makes her way to the wreckage of the Sazabi that lies abandoned on the surface of Axis.