Plot Synopsis

Dog Mask's identity is unknown. When heinous criminals avoid punishment from the law, all citizens over 18 years old receive a text message polling them on whether that person should receive the death penalty. If more than 50% respond in favor of the death penalty, that person is killed by Dog Mask. Meanwhile, the police chase after Dog Mask and three people become involved.

Kim Moo-Chan (Park Hae-Jin) is the leader of the First Investigation Team at the Southern Police Agency. He only cares about his career at the police agency.

Kwon Seok-Joo (Park Sung-Woong) used to be a famous legal scholar, but he killed the rapist who attacked his young daughter and then turned himself in to the police. He is now in prison and he is called Professor by the other prisoners.

Joo Hyun (Lim Ji-Yeon) is a police officer who has worked at the Cyber Safety Bureau at the Seoul Metropolitan Police Agency for 5 years.