Humanity finds a god machine on an alien world and immediately starts a war it cannot win. Every choice to survive makes the next catastrophe worse, until the ending stops pretending anyone gets out of this alive. Tomino built a mecha show that treats its finale like an apocalypse, not a victory lap.

Searching the universe for knowledge, humanity uncovers the relics of a long-vanished alien civilization on the planet Solo: three large vehicles and a huge spaceship. While Earth's team is excavating, the humanoid Buff Clan arrives. Karala Ajiba, daughter of the Buff Clan's military leader, lands on the planet against orders, and the search for her leads the Buff Clan to attack and wipe out the Earth settlement. Cosmo Yuuki, Kasha Imhof and Bes Jordan climb into the vehicles, which combine into the giant robot Ideon, while the other survivors escape aboard the Solo Ship. The Buff Clan keeps chasing them, hunting for Id, the mysterious energy inside the Ideon. The film is a recap of the Space Runaway Ideon TV series, built from footage of episodes 1 to 32, and it was first shown as half of a double feature.