Shogo Higuchi is a detective whose wife was murdered by a serial killer. Hikari Tachibana is a voice profiler whose father was murdered. She has a special hearing ability which allows her to hear minutiae sounds that other people do not. Victims in criminal cases call #110 which is connected to the emergency control room. To save people as quickly as possible, an investigation "emergency call response unit" is formed. Hikari Tachibana works in the emergency control room and gathers location information from callers with her special hearing ability. She passes on the information to Detective Shogo Higuchi in the emergency call response unit. Detective Shogo Higuchi then goes out with his team to save the victims. They must respond as quickly as possible during a crime's golden hour.

Kiriyama Shuichiro works as an information management officer in the prefectural police station. As he is very observant and has interest in the unresolved cases which have gone past the legal time frame (statute of limitations) i.e. the culprit cannot be charged even if he/she is caught, he investigates the cases without permission with the aim of "confirming" the culprit only. Some charateristics of this character would be his dark green spectacles, his wallet containing 20,000 yen at all times and he likes udon and nyuumen

Served as an undercover for several years, Leung Siu Tong or Laughing (Michael Tse) escaped from all calamity. Two years ago, he underwent special training, pretending to be mute and sneaked into an armed robbery gang as a spy. He successfully solved the criminal case and later became an instructor for special training in undercover work. Unfortunately he was unable to adapt to the stress in the discipline, so he applied to be an undercover once again. His supervisor Chief Inspector Jodie Chow Mong Ching (Fala Chen), looking exactly like his deceased girlfriend, was the person he communicates with during his undercover work. A female inspector and an undercover, falls into a black-white romance, and eventually became a pair that is in love, but cannot love…

Yeo Reum who just got her first job is Ji Hun’s girlfriend. Ji Hun who doesn’t have a specific job is a member of a band named Yellow. Yeo Reum is a realistic girl who works hard to be a decent grownup and she finds it hard to understand Ji Hun who has nothing but only Yeo Reum in his mind. One day, Ji Hun notices that Yeo Reum decided to break up with him and goes to meet her, and she really breaks up with him there. Ji Hun spends a year missing Yeo Reum, and one day, he receives a message from Yeo Reum.

There is a secret division in the Metropolitan Police Department that handles incidents that the Investigation Division can not investigate publicly. This is a suspense drama that heavily depicts the three cases of kidnapping, disappearance, and murder on the axes...

Living in an area known for its juvenile crime, 21-year-old Makoto is a friend of King, the leader of a youth gang called the G-Boys, though he himself does not want to join as a member. Known for his cool head and ability to get things done, Makoto becomes an key trouble-shooter for the gang by diffusing tense situations and keeping his friends out of harm's way. However, the death of his girlfriend and an escalating turf war with a rival gang threaten to be more than Makoto can handle.