In the world of Prester, flight serves as the primary mode of transportation, enabled by Claudia Fluid: a liquefied form of crystals produced on the planet. An organization known only as "the Guild" holds absolute authority over the skies, maintaining a monopoly on the engines that utilize this fluid. Furthermore, as ecological disasters destabilize the warring nations of Anatoray and Disith, the Guild also arbitrates disputes between them. Caught in the midst of this conflict are Sky Couriers, who pilot small, two-person vanships that fly freely through the sky. Last Exile follows the adventures of two teenagers who dream of surpassing their parents: Claus Valca, the son of a famous vanship pilot, and Lavie Head, Claus' best friend and navigator. Their work as couriers involves navigating the Grand Stream, an air current that separates the hostile nations and which even standard airships struggle to survive. However, when they accept a high-rated delivery to transport an orphan girl named Alvis Hamilton to the battleship Silvana, they are drawn into a much larger conflict that pits them against the might of the Guild.