Signal (2016) [Sigeuneol) is a South Korean police procedural television series starring Lee Je-hoon, Kim Hye-soo and Cho Jin-woong. It premiered on tvN on January 22, 2016 and the last episode appeared on March 12, 2016. The series was inspired by real-life criminal incidents in Korea, including the Hwaseong serial murders.
Met with widespread acclaim, Signal (2016) was liked by both audiences and critics, for its story and for the performances of its cast. It became one of the highest rated dramas in Korean cable television history.
In 1986 a mysterious walkie talkie allows a detective, Lee Jae-Han (Cho Jin-Woong) to communicate with a cold case profiler, Hae-yeong Park (Lee Je-hoon) from 2015; with the power of fore and hindsight and the help of another detective, Cha Soo-hyeon (Kim Hye-su) they not only solve crimes, but prevent them from ever taking place. Based on real unsolved murder mysteries, these three detectives transcend time in their quest for truth and justice.