Signal

A cold-case profiler in 2015 and a detective in 1989 work together to solve a series of related murders spanning three decades using a special walkie-talkie to communicate with each other.

Signal is a 2016 drama crime movie, starring Kim Hye-su, Lee Je-hoon, Cho Jin-woong. It holds an IMDb rating of 8.4/10 from 12,189 votes and runs 1h 20m.