In Universal Century 0068, Zeon Zum Deikun, newly appointed leader of space colony Side 3, declares independence from the Earth Federation; orphaned children Casval and Artesia survive a purge and go into hiding.

With Deikun's death, conflict intensifies between the Zabi and Ral families; to escape the political strife, Deikun's orphaned children Casval and Artesia say farewell to their mother and depart for Earth with Jimba Ral.

Changing their names to Édouard and Sayla, Casval and Artesia begin new lives on Earth as the children of Teabolo Mass, but are attacked by assassins dispatched by Kycilia.

Sayla and Édouard are grief-stricken by the death of their imprisoned mother; Édouard swears revenge upon the Zabis and devises a plan when he learns that the Aznable family's son Char is entering the Zeon military academy.

At Side 3, Dozle's development of humanoid mobile weapons makes dramatic progress with the assistance of Dr. Minovsky; at the military academy, Char befriends Garma and urges him to attack the Federation Forces barracks.

The military academy students launch an armed uprising under Garma's command and attack the Federation Forces barracks; Lino, who knows Char's true identity, is killed in the fighting thanks to Char's behind-the-scenes manoeuvring.