"Gundam Wing: Endless Waltz" is a three-episode OVA and later a theatrical film that serves as a sequel to the 1995 anime series "Mobile Suit Gundam Wing." Set in the year After Colony 196, the story takes place one year after the events of the original series, where the Gundam pilots have seemingly achieved peace by dismantling their mobile suits and scattering them into the sun. However, the fragile peace is threatened when a rogue faction within the Earth Sphere Unified Nation, led by Mariemaia Khushrenada, stages a coup to seize control of the government. Mariemaia, the daughter of the late Treize Khushrenada, aims to continue her father's vision of a world ruled by conflict and war.

The Gundam pilots—Heero Yuy, Duo Maxwell, Trowa Barton, Quatre Raberba Winner, and Chang Wufei—are drawn back into action as they uncover the coup and its implications. Relena Peacecraft, now a prominent political figure advocating for peace, is kidnapped by Mariemaia's forces, further escalating the crisis. The pilots must retrieve their Gundams, which were secretly preserved by their engineers, to confront the new threat. Each Gundam is upgraded with enhanced capabilities, reflecting the pilots' growth and the evolving stakes of their mission.

The narrative explores themes of war, peace, and the cyclical nature of conflict, as the characters grapple with their roles in shaping the future. Heero Yuy, the stoic and determined protagonist, faces internal conflict over his purpose and the morality of using violence to achieve peace. Duo Maxwell provides a more lighthearted yet resolute perspective, while Trowa Barton and Quatre Raberba Winner reflect on their past actions and the consequences of war. Chang Wufei, driven by a strict code of honor, struggles with his ideals in the face of a world that seems to reject them.

The climax centers on a battle in space, where the Gundam pilots confront Mariemaia's forces and her mobile suit, the Tallgeese III. The conflict culminates in a decisive showdown that forces the characters to confront the legacy of war and the possibility of a lasting peace. The story concludes with the Gundam pilots once again dismantling their mobile suits, symbolizing their hope for a future free from conflict. "Gundam Wing: Endless Waltz" serves as both a continuation and a resolution to the themes and character arcs introduced in "Gundam Wing," offering a poignant exploration of the cost of war and the enduring struggle for peace.