SGM Jeanne leads her squad on unapproved recon maneuvers even though the army is on alert due to a recent attack on the Development Center on the moon, Alpha. Meanwhile, the Zor have arrived around Glorie and one of their city ships begins the decent into the atmosphere.

The Southern Cross Army manages to decode and decipher a number of transmissions from inside the large Zor ships. With the information learned, the Southern Cross High Command has decided to launch a pre-emptive strike against one of the Zor city ships.

SGM Jeanne volunteers herself and members of her squad to assist in a mission to try to break through the Zor blockade and contact Liberty for assistance in repelling the Zor forces. When the engines of Lt. Borg's shuttle refuse to shutoff, the shuttle plows into the energy barriers of one the Zor ships and attracts fire from the Zor forces.

Jeanne and Bowie move their patrol into an out-of-bounds territory near some old ruins. They encounter Seifriet and a landing ship exploring the area. Bowie's Flash Clapper is destroyed and he is captured.

Corporal Louis Ducasse figures out a plan to disable the drive system on the large Zor space ships. The 15th is dispatched to enact a plan.

The members of the 15th squad prepare to explore the downed Zor space ship to learn about their foe. Bowie does some soul searching and wonders whether if he wants to be a member of the military, when his real dream is to be a pianist.

The 15th squad is cut off from the Southern Cross command by the Zor commanders. They split up in an attempt to gather more information and to find a way back out. Bowie meets Musica, the decisive one of the musical triad. Meanwhile, the Zor fleet commanders contact Claude Leon and offer a peaceful settlement if the humans agree to become biohumans, like Seifriet.

The captured bioroid is analyzed and the pilot is determined to be an advanced android despite Jeanne's pleas to the contrary. Later, the Zor launch an attack on the population centers of Glorie to gather more biohumans to pilot the bioroids.

Bowie introduces Jeanne to George Sullivan, a Lieutenant in the Special Technical Corps who is trying to determine a way to destroy the Zor vessels after his sister was killed in a Zor attack. Meanwhile, another of the Zor vessels descends to rescue the downed flagship.

Seifriet is taken in for questioning after being found by Lana, barely conscious on the battlefield. Major George Lombard arrives from the Liberty Patrol fleet to assist Glorie against the Zor. The Southern Cross High Command is disturbed when they realize this is the only help Supreme Commander Reinhardt has sent from Liberty.

General Emerson sees to it that Seifriet is taken to a doctor of his choosing so that this biohuman isn't destroyed like the last one. Efforts to restore his memory prove useless, so he is moved to a military hospital in attempts to remind him of his military background.

Impressed by Jeanne's results in jogging Seifriet's memories, General Emerson has him assigned to the 15th ATAC squad. A number of the squad members have difficulties accepting Seifriet into the ranks considering their fellow squadmates whom he has slain.

Supreme Commander Leon is tired of their numerous defeats and decides to take the offensive with a new weapon called Auroran, a transformable helicopter. The Tactical Space Corps takes a beating and 2LT Marie Angel manages to rally the troops and retreat to a base on the moon Alus. Meanwhile, back on Glorie, Jeanne decides to take Seifriet to the mounds containing the Zor ruins.

The Zor are utilizing Seifriet's implants to learn the plans of the Southern Cross Army. A relief fleet of at least 13 battlecruisers is dispatched to reinforce and revitalize the Aluce Development Center.

Supreme Commander Claude Leon decides to mount a two-pronged attack on the Zor by forming a large attack fleet. He places General Rolf Emerson in command of the offensive along with all the officers who disagree with the Commander's policies. Meanwhile, PSC Charles de Etouard decides to have some fun with Marie by leaving her waiting for their date.

Emerson tries to slip his fleet past the Zor forces and reinforce the moon bases. The Zor let him think he has escaped before unleashing forces in pursuit. To complement forces, Transport Squadron 85 arrives from deep space with additional troops and supplies. Meanwhile, The Zors experiment with a new control system for their Bioroids, the Biopsycher.

While playing video games with Jeanne, Louis invents an optical tracking system that follows where the user looks and targets where they focus. Two officers from the Special Technical Corps approach Louis to use this design for training. Meanwhile, The 15th ATAC launches with the next wave to assault the Zor flagship, but the Biopsychers are out in full strength providing strong resistance.

Seifriet escapes from Jeanne and Andrejz and they eventually rejoin the rest of their band. The group finds the civilian population center within the ship and attempts to blend in to avoid capture. However, when the squad is brought to the attention of the guards, they split into two groups inside the Zor large city ship as they search for a means to destroy it.

"In the far future, in the year 2120, humanity has left the Solar System and started the colonization of other planets. One of the farthest colonies is located in the terraformed planet Glorie. The powerful army of the Southern Cross protects the colonists from any unknown dangers. However, unbeknownst to the humans, Glorie is also the ancestral home of the Zor, a highly advanced race of nomadic humanoid aliens who have returned to reclaim their world."

The 15th squad sneaks Musica past the GMP by dressing her up as a soldier. While at the 15th ATAC headquarters, Musica sings an old song about a flower that is the center of the Zor civilization. Jeanne hears this and wonders if they are the flowers found in the Zor ruins.

Bowie takes Musica to the Zor ruins. Meanwhile, Lana forces Jeanne and her squad to assist in locating the AWOL Bowie and the Zor spy.

Supreme Commander Claude Leon launches the entire fleet against the Zor in an all-or-nothing attempt to destroy them. General Emerson is tasked with not letting the Zor through to the planet.

The Zor Fleet Commanders answer the all-out assault from the Southern Cross forces with an offensive of their own. The flagship is dispatched to recover the Protozor from the ruins while the others destroy the fleet and inhabitants. Eventually, The Zor commanders reveal their origins.