In Chicago during the early 1930s, the legendary transcontinental train, Flying Pussyfoot, embarks on a journey that will soon be stained with blood across the nation. Meanwhile, in New York, the determined scientist Szilard, alongside his reluctant assistant Ennis, hunts for lost vials of an elixir promising immortality. As mafia conflicts escalate, a war brews among the criminal factions. Simultaneously, aboard the Advena Avis in 1711, alchemists face the harrowing truth about the cost of eternal life. Adapted from the acclaimed light novels, this anime weaves a complex narrative of seemingly disparate events unfolding across time and space, interwoven by themes of alchemy, survival, and the thirst for immortality. At the center of this intricate web are the compassionate duo of would-be thieves, Isaac and Miria, whose paths intersect diverse characters driven by their own clandestine motives and desires, forging enduring connections and enduring repercussions for all involved.