As Heero and Zechs come to the end of their final duel, the battleship Libra and Peacemillion descend upon the earth threatening to engulf the world in a never ending winter.... Meanwhile Trowa helps out the wounded Quatre, and Duo delivers the "lords of plague" to peacemillion, in the hopes of averting the tradgedy of the battleships plunge.

Treize Kushrenada's plans to destroy the Alliance come to a head when the leaders of the Alliance hold a meeting. The meeting is led by Marshal Noventa and outlines his peace agenda. However, based on Treize's false intelligence, the Gundams destroy the Alliance leadership, and Oz begins to take over Earth.

A Mobile Suit with fantastic power is on a rampage. It's attacking the colonies one after another in a brutal display of raw power. Trowa and Heero move to intercept this strange new Mobile Suit and are surprised by who its pilot is...

Relena's plead for her brother to stop the war goes unheeded. The Gundam pilots battle their way though a fierce encounter with Mobile Dolls under Dorothy's control.

The five Gundams launch their ultimate offensive knowing that only mass slaughter and a sad battlefield awaits them. The Peacemillion space fortress rams the Libra to block White Fang's way to Earth, even if it will bring their own death.

While Wufei fights Treize, Quatre fights Dorothy, Trowa tries to change his destiny, Duo frees the scientists, and Heero looks for Milliardo for the last round of their duel.

Lady Une briefs her troops on another strategy to try and wipe out the Gundams. Heero and Zechs face each other again, but this time it's the Wing Gundam versus the Tallgeese.

Trowa and Heero must battle their crazed friend; but they find themselves losing against this new Gundam. Treize, meanwhile, disapproves of the Romefeller Foundation's plan to use Mobile Dolls-automated Mobile Suits without pilots. His dissension results in his arrest by OZ.

Milliardo leaves Quinze in command temporarily as he takes a rest. The Mercurius and Vayeate are once again used against the Gundams. However, this proves to be the two Mobile Suits' last battle.

The United Earth Sphere Alliance collapses, sending the entire Planet into a panic. This allows OZ to step forward and take control through a well planned coup. Zechs is occupied with other things: he is searching for the ruins of the Sanc Kingdom.

Relena, now a prisoner of the Romefeller Foundation, is faced with a very difficult choice. Meanwhile Heero and Zechs engage in battle once again-this time on the grounds of the Sanc Kingdom.

Lady Une makes the Gundams her next target and activates the self-destruct sequence on the New Edwards Base. Can Heero prevent the explosion of the New Edwards Base and find the person who set them up? Meanwhile, Wufei duels with Treize.

Duo and Trowa are reunited and team up against the enemy once more. Meanwhile, the Romefeller Foundation has mounted a final assault against the Sanc Kingdom, forcing Relena to surrender to prevent a battle.

Heero manages to get into the Libra and reunites with Relena to confront Milliardo. Treize challenges Milliardo with his new Tallgeese II Mobile Suit. To try and eliminate Treize, he fires the Libra...

Relena goes back to Earth. Wufei attacks another Alliance base and Trowa has started to work in a circus as a cover. Back at school, Relena tells Heero that she knows everything about him and invites him to a party, to be held that night.

At the South Pole, Zechs waits with the newly-rebuilt Wing Gundam. After Herro arrives and the rematch begins, Relena arrives and tries to stop them from wasting their lives. However, she discovers a revelation...

A wild Mobile Suit approaches the colonies at high speed; Lady Une orders test pilots Heero and Trowa to stop it. Meanwhile, Quatre, exhausted from the pressure of his missions, returns home for a visit. But what he finds there is not comfort, only more chaos and tragedy.

With Lady Une's help, Duo escapes from OZ and goes to destroy the Mobile Suit production base on the moon. But while there, he meets a girl named Hilde who has become a soldier. The choice is suddenly much more complicated.

Zechs gets the Wing Gundam Zero and demolishes the OZ forces. However, Treize gives Heero a new Gundam, perhaps the most terrible Gundam of all, and its name is Epyon...

A group of rebel colony citizens calling themselves the "White Fang" starts attacking OZ bases. Quatre and Noin search for the other Gundam pilots. The Romefeller Foundation names Queen Relena as their representative.

Quinze, the leader of the White Fang, contacts Zechs and asks him-and his Gundam-to join their cause. Still suffering from amnesia, Trowa once agian goes into battle.

As Relena takes her first step towards trying to achieve true peace, Heero sets out to eliminate her. Milliardo Peacecraft, the new leader of the White Fang, is now intent on going to war against OZ, the Romefeller Foundation and the Gundam pilots.

With Milliardo Peacecraft's declaration of war against the Earth in effect, the battle rages on between the White Fang and OZ. Meanwhile, Treize returns to take control of the Romefeller Foundation, forcing Relena to step down. In space, the Gundam pilots encounter Milliardo and his Epyon.

Relena and her father, Vice Foreign Minister Darlian, journey to the colonies to try and prevent war. but there are those who do not want peace. Amidst the grief and tragedy, Relena learns her true identity...

The Gundams have been defeated. With the colonies used as shields, the pilots don't have a chance. No one knows whether Heero is dead or alive. On the trail of her father's killer, Relena heads to Moscow. Duo and Quatre take refuge with the Maguanac Corps.