"Mobile Suit Gundam Thunderbolt: Bandit Flower" is a sequel to the original "Mobile Suit Gundam Thunderbolt" ONA series, continuing the story set in the Universal Century timeline during the One Year War. The narrative centers on the conflict between the Earth Federation and the Principality of Zeon, with a focus on the South Seas Alliance, a Zeon remnant faction operating in Southeast Asia. The South Seas Alliance, led by Commander Burroughs, seeks to secure a powerful new weapon, the Psycho Zaku, to regain control over the region.

The protagonist, Io Fleming, a skilled but reckless pilot from the Earth Federation, returns as the primary character. Io pilots the Full Armor Gundam, a heavily armed mobile suit designed for combat in the Thunderbolt Sector. His rival, Daryl Lorenz, a Zeon sniper and former pilot of the Psycho Zaku, also returns, now using a new mobile suit, the Atlas Gundam, which is adapted for amphibious warfare. The dynamic between Io and Daryl remains a central theme, exploring their mutual respect and rivalry as soldiers on opposing sides.

The plot revolves around the South Seas Alliance's efforts to recover the Psycho Zaku and the Federation's mission to prevent them. The Alliance captures a Federation transport ship, the Spartan, which carries critical data and resources. Io and his team are tasked with rescuing the Spartan and thwarting the Alliance's plans. The story delves into the psychological toll of war on soldiers, particularly through Daryl's struggles with his prosthetic limbs and his desire to prove his worth despite his physical limitations.

The narrative also introduces new characters, such as Claudia Peer, a Federation officer who becomes a key figure in the mission, and Commander Burroughs, whose ruthless tactics and ambition drive the Alliance's actions. The conflict escalates as both sides engage in intense battles, showcasing the destructive power of mobile suits and the high stakes of the war. The story concludes with a climactic confrontation between Io and Daryl, highlighting their personal vendetta and the broader implications of their actions within the war.

"Mobile Suit Gundam Thunderbolt: Bandit Flower" maintains the gritty, war-torn atmosphere of its predecessor, emphasizing the human cost of conflict and the moral ambiguities faced by its characters. The series balances action-packed mobile suit battles with character-driven drama, providing a compelling continuation of the Thunderbolt saga.