Seit dem letzten Kampf zwischen der Celestial Being und den UN Gruppen sind vier Jahre vergangen. Um die Rechte und Anliegen der Menschen weiter zu unterstützen und die Gemüter der Überlebenden zu beschwichtigen, wird eine unabhängige Armee, die A-Laws gegründet.
The Earth Sphere Federation's autonomous peacekeeping force "A-LAWS", has been suppressing an opposition force called "Cataron", using inhuman tactics and extermination. Saji Crossroad has been working as an engineer on the "Proud" Colony, a space station under construction. When a coworker is discovered to belong to Cataron, Saji is arrested under false charges by A-LAWS and pressed into forced labor. Cataron forces mounts a rescue, but A-LAWS mobile suits appear with orders to exterminate the rescuers and all station personnel to cover up its forced labor operation. Setsuna F. Seiei, infiltrates the colony during the battle and rescues Saji. Setsuna then engages the A-LAWS suits in Exia. Still damaged from its battle four years prior, Exia is no match for A-LAWS' new "Ahead" mobile suit. Setsuna is saved at the last moment by the appearance of Tieria in his new Seravee Gundam. Brought back to Celestial Being's new mothership, Ptolemios II, Setsuna is confronted by Saji who now knows Setsuna's identity as a Meister. Once again joining Celestial Being, Setsuna returns to Earth to recruit Lyle Dylandy as the new "Lockon Stratos".
Quatre ans ont passé, et l'équipage de Celestial Being ne sait toujours pas si Setsuna est vivant. Une attaque sur la colonie Proud où se trouve Saji Crossroad se prépare, et laisse supposer que cet événement de grande ampleur fera revenir le pilote de l'Exia.
地球圏連邦・独立治安維持部隊「アロウズ」は反政府勢力「カタロン」の鎮圧を行っていた。シーリンに建設途中のコロニー「プラウド」そのコロニーでは、技師となった沙慈が働いていた。
地球圈联邦‧独立治安维持部队“A-LAWS”，以不人道手段对反政府势力“卡达鲁”执行镇压、歼灭任务。纯源的干部克劳斯告知希琳，要加快在建设中的殖民地“荣誉”的同志救出作战。成为技师的沙慈在那个殖民地工作，却因为同僚是卡达鲁的成员而蒙上不白之冤，遭到A-LAWS的保安局人员逮捕，被送到高重力区进行强制劳动。
