Tomino builds a new Gundam world from scratch and immediately tears it down, asking what happens when a teenage pilot realizes the mobile suit is the only thing keeping him alive, and the only thing keeping everyone else dead. The F91 itself feels like a weapon designed by people who stopped caring about control, all speed and aggression with nowhere safe to land. Seabook never gets a moment to breathe between discovering his girlfriend's family are fascists and learning he's the only person who can stop them.

In Universal Century 0123, three decades after Char's Counterattack, the Crossbone Vanguard militia clashes with the Federation across Earth's space colonies. Led by Meitzer Ronah, the group aims to bring back rule by the nobility through a new order called Cosmo Babylonia. When fighting reaches the home colony of teenager Seabook Arno, he and his friends are forced to flee and are pulled into a conflict that is spiraling into full war. Seabook meets Cecily Fairchild, Ronah's granddaughter, and circumstance puts him in the cockpit of the F91 Gundam, a mobile suit his estranged mother, Dr. Monica Arno, helped design. He must decide whether to defend the Federation's existing order or join Cecily in seeking a better path for everyone. The film is a mecha science fiction drama.