You save a boy's life instead of a mayor, and that one choice becomes a manhunt that lasts 74 episodes because the boy you saved might be a serial killer. Tenma spends the entire show chasing the consequences of his own mercy, watching his decision ripple into mass murder and realizing that doing the right thing doesn't come with answers, it comes with blood on your hands. The show moves like a nightmare where you're always one step behind, catching glimpses of a monster shaped like a child, never sure if you're hunting evil or creating it.

A Japanese surgeon in Germany makes a choice that changes everything. When a critically wounded boy and a powerful mayor both need immediate surgery, Dr. Kenzo Tenma saves the child instead of the patient whose support the hospital was counting on. He believes every life is equal, but the consequences ripple outward in ways he never anticipated. Murders start happening. People connected to Tenma begin dying under suspicious circumstances, and suspicion falls on the doctor himself. As more killings occur around him, Tenma comes to suspect that the boy he saved that night is tied to all of it, and that his single act of compassion may have unleashed something monstrous into the world. What follows is a psychological hunt that questions whether saving a life was salvation or catastrophe. Tenma abandons his medical career and sets out across the country to uncover the truth about the boy. Dark, methodical, and genuinely unsettling, this thriller trusts its audience to piece together a complex mystery alongside its protagonist.