A distant future… Since humanity left a resource-deprived, lifeless Earth, it has split into three races: the genetically modified Dactians, the half-mechanical Saitens, and the maromannites packed with nanobots. Only the “savages” vilders who inhabit the planets devastated by galactic expansion have preserved their human nature. Many centuries later, alarming reports began to come from the center of the Galaxy, called the Furnace. The chance to figure out what’s going on falls to a maromannite officer, Max Hauer, and a Dactian tactician, Cyrus Rem, when a mysterious ship—“Steel Butterfly,” missing for many years—appears unexpectedly in the outer sector near the Furnace.