

The series ran 2 seasons across 24 episodes and has ended. Streaming on Netflix, Prime, and Tubi.
Synopsis
Detectives from the present and a detective from the past communicate via walkie-talkie to solve a long-time unsolved case.
Ratings
| Source | Rating | Weight |
|---|---|---|
| IMDb | 8.4/10 | 71% |
| TMDB | 8.2/10209 votes | 29% |
| Balasaur Score | 83 | 100% |
Seasons
| 1 | Season 1 | 16 ep2016 |
| 2 | The Second Signal | 8 ep2026 |
Key crew
- Kim Eun-heeCreator
- Kim Won-sukCreator
Cast
- Lee Je-hoonPark Hae-young
- Kim Hye-sooCha Soo-hyun
- Cho Jin-woongLee Jae-han























