The game begins with Dingo Egret, the protagonist, working at a mining facility on Callisto. He inadvertently discovers the Orbital Frame, Jehuty, that was hidden there by Leo. When he is attacked by BAHRAM forces who have come to seize it, Dingo climbs into Jehuty and engages the attackers. During the battle, Dingo enters the BAHRAM battleship, seemingly defeating Nephtis, an Orbital Frame controlled by an A.I. program based on Viola's fighting style, but is subdued by Anubis, Jehuty's superior counterpart controlled by Col. Ridley (Nohman) Hardiman, leader of BAHRAM.
As a prisoner, Dingo is assaulted by Ken Marinaris, a female Orbital Frame runner that Dingo defeated in the previous battle. Nohman arrives moments later and asks Dingo to join him. When Dingo refuses, Nohman shoots him, ordering Ken to dispose of the body. Instead, Ken has Dingo revived and placed inside Jehuty. When he comes to, she explains that Jehuty is acting as a life-support system, and if he leaves Jehuty, he will die. She then tells him that she is a UNSF spy. Dingo escapes with Taper and heads for Mars.