7.5/10 is my rating. This is a 2016 South Korean crime drama with 16, 60 minute, episodes. Lee Je-hoon Kim Hye-soo and Cho Jin-woong. The story is inspired by the Hwaseong serial murders in Korea as well as other true crimes.

A newbie detective/profiler, Park Hae Young (Lee Je Hoon), finds a walkie talkie that is broadcasting through time from Hae Young's time of 2015 from 2000. Hae Young has been assigned to a cold case unit who is tasked with solving crimes where the trail of evidence has gone cold. It is more of a political move than any real attempt to solve the crimes in terms of the "higher ups." On the other end of the line is Lee Jae Han (Jo Jin Woong) who is able to get clues from Hae Young about crimes that "occurred" and change or prevent the events. Cha Soo Hyun (Kim Hye Soo) is a female detective who leads the cold case team. She knows Jae Han well as she was once a rookie on his team.

Spoiler ? I liked this but what slightly ruined it for me was it ended very nebulously. Some like it when it "leaves you to wonder" - I am not one of them. I understand there MAY be a second season but without that being a certainty the ending just didn't do it for me. I liked all the characters, the suspense and cases, but the ending is what really determined how I felt about this overall. Many really liked this - it rates very high. A lot of folks rate this higher than Tunnel. I preferred Tunnel. That had similar intrigue and was based on some of the same real murder cases. However, that story for me was more logically flowing and the ending felt complete. Worth the watch but be aware the ending is not neatly tied up.