"Fullmetal Alchemist the Movie: Conqueror of Shamballa" serves as a direct sequel to the 2003 "Fullmetal Alchemist" anime series, continuing the story of Edward and Alphonse Elric. The film is set in an alternate version of 1920s Munich, Germany, where Edward has been stranded after the events of the series. Separated from his brother Alphonse, who remains in their original world, Edward struggles to adapt to a world without alchemy, relying instead on scientific advancements to find a way back home. Meanwhile, Alphonse, still in their world, works tirelessly to reunite with his brother, using alchemy to search for a portal between dimensions.

In Munich, Edward encounters a group of impoverished Romani people, including a young woman named Noah, who becomes a key figure in his journey. The city is rife with political and social unrest, with rising tensions between the impoverished and the elite. Edward’s presence attracts the attention of a secretive organization led by Dietlinde Eckhart, a fanatical woman obsessed with creating a utopia called Shamballa. Eckhart believes that by harnessing the power of the Thule Society and a mysterious artifact known as the "Gate," she can bridge the two worlds and achieve her vision of a perfect society.

As Edward investigates the Thule Society’s activities, he discovers their plans to use the Gate to invade his original world, exploiting its resources and alchemical knowledge. This revelation forces Edward to confront his own moral dilemmas, as he must decide whether to prioritize his personal goal of reuniting with Alphonse or prevent the catastrophic consequences of the Thule Society’s ambitions. Meanwhile, Alphonse, in their original world, uncovers a similar plot involving the Gate, leading to a climactic convergence of the two worlds.

The film explores themes of sacrifice, brotherhood, and the consequences of human ambition. Edward and Alphonse’s bond remains central to the narrative, driving their actions and decisions. Supporting characters, such as Noah and Eckhart, provide additional layers to the story, highlighting the contrast between empathy and fanaticism. The climax involves a dramatic confrontation between the brothers and the Thule Society, culminating in a bittersweet resolution that underscores the cost of their journey and the enduring strength of their relationship.