"Mobile Suit Gundam G40" is a short anime film that reimagines the original "Mobile Suit Gundam" story with a modernized aesthetic and streamlined narrative. The plot centers on the conflict between the Earth Federation and the Principality of Zeon during the One Year War. Amuro Ray, a young civilian, becomes the pilot of the RX-78-2 Gundam, a powerful mobile suit developed by the Federation, after Zeon forces attack his colony, Side 7. The Gundam is a key weapon in the Federation's efforts to counter Zeon's technological superiority.

Amuro's journey begins as he reluctantly takes on the role of a soldier, grappling with the responsibilities and moral dilemmas of warfare. Alongside the crew of the White Base, a Federation warship, he faces numerous battles against Zeon's elite forces, including the skilled and enigmatic Char Aznable. Char, a masked Zeon officer, becomes Amuro's primary rival, driven by personal motives and a desire to prove his superiority. The narrative explores themes of survival, the psychological toll of war, and the evolving relationship between Amuro and his fellow crew members, including Bright Noa, the disciplined commander of the White Base, and Sayla Mass, a mysterious figure with ties to Char.

The story condenses key events from the original series, focusing on pivotal battles and character interactions while maintaining the core conflict between the Federation and Zeon. The film emphasizes the technological advancements of mobile suits and their impact on warfare, as well as the personal growth of Amuro as he transitions from an inexperienced youth to a capable pilot. The reimagined visuals and updated designs provide a fresh perspective on the classic tale, offering a concise yet impactful retelling of the original "Mobile Suit Gundam" narrative.