Monster begins in Germany, where Dr. Kenzou Tenma is an elite Japanese neurosurgeon climbing the ranks of a major hospital and preparing to marry Eva Heinemann, the daughter of the hospital director. One night, he is ordered to leave one operation and save a famous performer instead. Tenma obeys, and the successful surgery earns applause from the director, his fellow doctors, and his fiancée, but the poor immigrant worker he did not treat dies. The loss leaves Tenma with a crisis of conscience that defines the rest of his life. When another choice arrives, this time between the young Johan Liebert and the town's mayor, Tenma refuses to follow orders and saves Johan instead. The decision destroys his social standing and places him at the center of a mysterious sequence of deaths involving the director and two other doctors. With no evidence to convict him, Tenma is released and his position within the hospital recovers.
Nine years later, after Tenma saves the life of a criminal, the consequences of that night return in the worst possible way. He comes face to face with the monster he once operated on and begins a relentless search to make amends for the havoc spread by the life he saved. As Johan's twin sister Anna Liebert pursues the truth of their past, inspector Heinrich Runge closes in on Tenma, and Eva remains tied to the wreckage left behind by their broken engagement. Monster unfolds as a psychological thriller about guilt, responsibility, and the devastating reach a single act of mercy can have across many years.
