The Federation forces are routed in the face of the onslaught of the Zeon Zakus during Earth Drop Operations. When the main forces are retreating for resupply, Lt. Ben Barberry, who leads an anti-mobile suit special tactical squad utilizing the "Regina" missile launcher, is ordered by his arrogant superior, Col. Michael Colmatta, to advance and ambush the pursuing Zeon forces.

Sgt. Rayban Surat is transferred to the 1st Platoon, 301st Tank Squadron of the Federation's 44th Hybrid Regiment to become the driver for Lt. Harmon Yandell, a seasoned ace of the variant-5 Type 61 tank.

Though Operation Odessa is proceeding, the 44th Hybrid Brigade suffers setback after its advance is bombarded by artillery from Zeon's Dobday-class land battleships. They are reinforced by three Guntanks piloted by a trio of convicts led by Lt. Arleen Nazon, a technical officer blamed and condemned to rot in jail after her lover defected to Zeon with information of the RTX-440 project.