In the midst of ongoing protests by citizens of the Martian colony Chryse demanding independence from the Earth government, the Chryse Guard Security is assigned to protect Princess Kudelia Aina Bernstein on her diplomatic mission. When the CGS headquarters is suddenly attacked by Gjallarhorn forces, the Third Army Division, having just been abandoned by their superiors, strike back with the ancient Gundam Barbatos, piloted by Mikazuki Augus.

The adults of CGS flee in the face of Gjallarhorn's attack, using Mikazuki and the other children as decoys. Gathering the children who have been left behind, Orga decides to fight back against Gjallarhorn, and puts a certain plan into motion.

Thanks to Mikazuki and the Gundam Barbatos, Orga's group has temporarily repulsed Gjallarhorn, though not without many sacrifices. As they are discussing their next move, one of Gjallarhorn's Graze mobile suits again appears at the CGS base.

Kudelia is distressed that so many boys have lost their lives because of her. Mikazuki takes her to the farm run by Biscuit's grandmother, where an unexpected encounter awaits.

Kudelia and Tekkadan finally leave Mars behind them and head for Earth. With a ship waiting for them, they attempt to travel by shuttle to a low-orbital station, but are attacked by Coral's Gjallarhorn forces.

The members of Tekkadan need a guide in order to reach Earth despite Gjallarhorn's surveillance. To gain a powerful backer, they attempt to negotiate with Teiwaz, which is based in the Jupiter Sphere.

Tekkadan has made contact with Turbines, which runs Teiwaz's transport division. But they find themselves clashing with Turbines over their group's origins and property.

Having demonstrated Tekkadan's strength and legitimacy to Naze, the leader of Turbines, Orga and the others renew their negotiations with Teiwaz. Meanwhile Atra visits Turbines's warship, bringing the frustrated Kudelia with her.

Accompanied by Naze, Tekkadan visits the Saisei, the stronghold of Teiwaz, in order to meet with Teiwaz's representative McMurdo Barriston. Here, Orga receives a surprising proposal from Naze.

Tekkadan and Turbines go on ahead to Earth, leaving Mikazuki and Yukinojo on the Saisei to complete final adjustments to the Barbatos. But the events aboard the Saisei have greatly affected their respective states of mind.

While on patrol, Akihiro and Takaki encounter unknown enemies and engage them in battle. The attackers turn out to be Brewers, a pirate group that operates between Mars and Earth.

Mikazuki and Orga learn that Akihiro's long-lost younger brother is one of the Brewers mobile suit pilots. Tekkadan challenges Brewers in order to get back Akihiro's brother.

The battle with Brewers has cost many lives on both sides. The survivors hold a funeral service to pray for the rebirth of their fallen comrades.

After overcoming many difficulties, Tekkadan is finally about to reach Earth. Its members head for the Dort colony cluster, to deliver an item that Teiwaz asked them to transport when they were aboard the Saisei.

Just as on Mars, the colonies suffer great disparities with Earth, and a protest movement has begun among the increasingly dissatisfied workers. As it gradually intensifies, Tekkadan is caught up in various schemes.

The colony workers have launched a protest movement against the company that employs them. As they grow more radical, the situation finally develops to the point of a Gjallarhorn intervention. Before she knows it, Kudelia has been drawn into the heart of the uprising.

Kudelia and Tekkadan witness Gjallarhorn's brutal suppression of the workers. Seeing the true situation of the colonies, Kudelia makes a fateful decision.

Tekkadan's members attempt to leave the colonies behind and descend to Earth at last, but they miss their chance due to one last item of business in the colonies. They are contacted by someone who claims to be their supporter.

Following a resupply by the Montag Company, Tekkadan prepare their descent to Earth, with a Gjallarhorn fleet standing in their way.

Tekkadan has finally made it to Earth, successfully introducing Kudelia to Arbrau's representative, Togonosuke Makanai. However, they will have to accompany Makanai to a parliamentary general session taking place in Edmonton.

During preparations to depart for Edmonton, Tekkadan finds itself under attack by Gjallarhorn. Setting a trap for their relentless pursuers, Orga makes a counterattack.

Though Tekkadan is exhausted by its repeated battles with Gjallarhorn, its members are still determined to get to Edmonton, and they hasten toward their goal.

As Tekkadan heads for Edmonton, it finds Carta blocking the way, seeking a showdown. However, Mikazuki and the others won't let their progress be halted, and they press on ahead.

Orga and the other Tekkadan members have finally reached Edmonton, but they are attacked by Gjallarhorn, which seeks to prevent Makanai from making it to the parliamentary session.

In the midst of the battle in Edmonton, McGillis reveals his true motives to Gaelio while Kudelia and Makanai make it to the parliament assembly in time. As Mikazuki and Ein engage in a bloody duel, Kudelia takes her stand to give one more speech to the world while Orga gives his comrades the order not to die on the battlefield.

Mikazuki's group, Tekkadan, is commissioned to escort Kudelia on an inspection of a halfmetal mine. Under Tekkadan's protection, she completes the inspection schedule without incident. But suddenly, Tekkadan finds itself under attack by space pirates.

Despite some casualties, Tekkadan successfully repulses the space pirates of the Dawn Horizon Corps. However, it appears that this enemy was just one part of a huge space pirate group, and Orga decides to counterattack in anticipation of further assaults.

Deploying all of its fighting strength, Tekkadan attempts to capture Sandoval Reuters, the leader of the Dawn Horizon Corps. Gjallarhorn's outer lunar orbit joint fleet Arianrhod also joins the battle, turning it into a three-way free-for-all.

Mikazuki and Orga visit Allium, leader of the ideological group Terra Liberionis, to resolve the issues surrounding the attacks of the Dawn Horizon Corps. Meanwhile, McGillis arrives at Gjallarhorn's Martian branch and offers Tekkadan a certain proposal.

Tekkadan's Earth branch, which is now serving as a military advisor to Arbrau, is consumed with preparing the launch ceremony for the Arbrau Defense Forces. At Makanai's request, Tekkadan takes charge of security for the ceremony venue.

A conflict between the rival economic blocs Arbrau and SAU breaks out as their armies clash on the Balfour Plain. Tekkadan also joins the battle under the command of Galan Mossa, but its members become exhausted as the war of attrition continues for days.

Gjallarhorn receives a mediation request from the SAU. In order to break the prolonged stalemate, McGillis personally enters the battlefield in a mobile suit. Galan's team launches an attack on McGillis, who is whittling down Arbrau's fighting strength.

The fighting ends as the rival economic blocs SAU and Arbrau agree to peace negotiations. As they remember their fallen comrades, the members of Tekkadan decide to withdraw from Earth.

Via a certain matter on Earth, the connection between Tekkadan and McGillis grows even stronger. Meanwhile, the Gundam Vidar, which has been undergoing adjustment by the Arianrhod fleet, finally rolls out.

Tekkadan has discovered a huge object at a mine it is managing. Having received a message from Orga about the object's true nature, McGillis decides to pay a secret visit to Mars.

The awakened mobile armor, along with a huge quantity of sub-units, heads for a densely populated area to begin its attack. Tekkadan attempts to hold back the onslaught, but is helpless against its overwhelming power and superior numbers.

Mikazuki faces off against the mobile armor. The battle continues with mounting intensity.

Lafter and the other Turbines members take their leave of Tekkadan. Meanwhile, at Teiwaz, the organization's number two Jasley Donomikols plans a new maneuver.

Tekkadan has been thwarted in its attempt to rescue Turbines from danger. Orga restrains himself in response to Naze's wishes, but...

A modest funeral service is held aboard the Saisei. But Jasley has been preparing yet another stratagem.

With the repairs to the Barbatos complete, Tekkadan musters its fighting strength. The members ready their resolve for the confrontation with Jasley.

Gjallarhorn's Earth headquarters has been captured in a coup d'état by young officers. Among them is McGillis, who heads for a facility underneath the headquarters.

The Arianrhod fleet, led by Rustal Elion, attempts to gather all its forces to fight the coup d'état.

After many complications, Tekkadan finally joins the battle against the Arianrhod fleet, but...

Tekkadan revives and launches an attack, aiming to escape the battlefield. Meanwhile, the fight between McGillis and Gaelio becomes increasingly ferocious.

Tekkadan plans to return to its Martian headquarters and start over. The situation, however, has undergone a dramatic reversal.

Tekkadan is in a difficult predicament. A huge Gjallarhorn force then begins deploying around its Martian headquarters.

Gjallarhorn intends to launch a mopping-up operation against Tekkadan. The hour of its commencement is drawing steadily closer...

Gjallarhorn begins its Tekkadan mopping-up operation. Facing this, Tekkadan's future is...