Signal (Season 1)

There are those who are born monsters, but there are also those who are made into monsters by people.

 Detectives from the present and a detective from the past communicate via walkie-talkie to solve a long-time unsolved case.

You're Doomed 8.3
Air date: 2016-01-22
Runtime: 67 min
Overview: Profiler Park Hae-young hears a man calling his name through a discarded two-way radio. The voice starts talking about an unsolved crime.
We Still Have a Chance 8.0
Air date: 2016-01-23
Runtime: 66 min
Overview: The statute of limitations is lifted after the suspect's arrest. Hae-young joins Soo-hyun's team for the newly established cold case squad.
We Can Prevent the Killings 8.0
Air date: 2016-01-29
Runtime: 65 min
Overview: Reality changes after Hae-young exchanges information with Jae-han. Hae-young tries to work together with Jae-han in 1989 to prevent the next murder.
We Found the Killer 7.8
Air date: 2016-01-30
Runtime: 65 min
Overview: The ninth victim is Won-kyung, the woman Jae-han loves. A driver turns himself in, but Soo-hyun and Jae-han determine that his son is the real killer.
Changing the Past Alters the Present 7.3
Air date: 2016-02-05
Runtime: 68 min
Overview: Hae-young starts to investigate Jae-han's disappearance. Jae-han's former colleagues get suspicious about seeing Hae-young digging into the past.
Catch Him by All Means 8.0
Air date: 2016-02-06
Runtime: 70 min
Overview: Seeking vengeance for the events that lead to the death of his daughter, Kyung-tae commits a kidnapping after getting out of prison for burglary.
We Must Dig Deeper 7.8
Air date: 2016-02-12
Runtime: 67 min
Overview: Jae-han arrests Se-kyu for the serial burglary case, but the culprit is freed after serving a short sentence; Kyung-tae still commits murder.
How Are You Alive? 8.5
Air date: 2016-02-13
Runtime: 74 min
Overview: Soo-hyun and Hae-young notice a connection between the burglary case and Da-hye, the woman who killed herself twenty years ago.
Hongwon Dong Case 8.2
Air date: 2016-02-19
Runtime: 74 min
Overview: Hae-young learns that Chi-soo and Jae-han met in 1999 during a case in Inju. After serving time for the crime, Hae-young's brother had killed himself.
Someone Has to Stop the Bad Guys 7.8
Air date: 2016-02-20
Runtime: 72 min
Overview: The bodies discovered in the mountains appear to be more victims of the 1997 serial murder case. Jae-han learns that Soo-hyun became team leader.
The One Last Case 7.3
Air date: 2016-02-26
Runtime: 78 min
Overview: Hae-young and Soo-hyun arrest Jin-woo after coming to the conclusion that he is the killer. Hae-young asks Jae-han about the Inju rape case.
The Case Was Manipulated 8.0
Air date: 2016-02-27
Runtime: 78 min
Overview: Hae-young becomes a suspect for the murder of Chi-soo. Jae-han realizes who the principle offender of the attack on Hye-seung is.
The Real Assailant 7.8
Air date: 2016-03-04
Runtime: 74 min
Overview: Soo-hyun and the others mourn after confirming that the remains belong to Jae-han. Hae-young learns that Jae-han used to look after him in the past.
Not Now, But Maybe In The Past 7.5
Air date: 2016-03-05
Runtime: 74 min
Overview: Hae-young realizes the possibility that his brother could have been murdered after learning from Hye-seung that Sun-woo was not guilty.
Is It Really You? 7.8
Air date: 2016-03-11
Runtime: 72 min
Overview: Hae-young is arrested for the murder of Chi-soo. Soo-hyun hears Jae-han apologizing over the radio for not being able to prevent Sun-woo's death.
If You Don't Give Up 8.0
Air date: 2016-03-12
Runtime: 89 min
Overview: Hae-young is in critical condition after being shot while meeting with Sung-bum. In 2000, Jae-han has been captured by Bum-joo.