In Hong Kong, a vigilante serial killer by the name "Darker" leaves death notices stating when and how he will murder a victim. Even if the victim reports it to the police and receives protection, Darker can easily break through and execute them. Ten years ago, Darker orchestrated a mysterious explosion of Mang Wan, the girlfriend of police inspector Luo Fei, with the only survivor and witness being Wong Siu Ping, a homeless man who was crippled and his face was severely burnt and disfigured as a result. Darker reappears again in the present, sending out death notices and executing violent and brutal punishments, challenging the police to a face-off with an unimaginable conspiracy behind them.