Kenzou Tenma, a celebrated Japanese neurosurgeon practicing in post-war Germany, confronts a harrowing dilemma: whether to operate on Johan Liebert, a dying orphan boy, or on the mayor of Düsseldorf. Ultimately, Tenma chooses to risk his standing by saving Johan, effectively abandoning the mayor to die. As a result of this decision, hospital director Heinemann dismisses Tenma from his post, and Heinemann's daughter Eva calls off their engagement. Disgraced and ostracized by his peers, Tenma sees all prospects of a successful career vanish—that is, until the mysterious murder of Heinemann presents him with a new opportunity. Nine years later, Tenma heads the surgical department and is on the verge of becoming director himself. Although his situation initially appears stable, he soon finds himself drawn into a series of gruesome murders occurring across Germany. The perpetrator is a monster—the very same one Tenma saved on that fateful day nine years prior.