Signal

January 22, 2016

Criminal profiler Park Hae-young (Lee Je-hoon) in 2015 receives a transmission on an old walkie-talkie from Detective Lee Jae-han (Jo Jin-woong) in 1989. They agree to share information across time to solve a cold case. The Incheon cold case unit and Hwaseong area establish both temporal worlds.

January 22, 2016

The first cold case they attempt to solve together — a murder from 1989 that was never resolved. The mechanism of their collaboration established.

January 29, 2016

Their first successful change to the past and its unexpected consequences in Hae-young's present.

January 29, 2016

Detective Cha Soo-hyun (Kim Hye-soo) — the woman whose life connects both timelines — is introduced.

February 5, 2016

The connection between their collaboration and the real Hwaseong serial murders — the drama's heaviest historical weight.

February 5, 2016

The full texture of Jae-han's 1989 world — the detective culture, the limited forensics, the specific difficulties of investigating in a pre-digital era.

February 12, 2016

The walkie-talkie connection becoming intermittent — the anxiety of a lifeline that might break.

February 12, 2016

Hae-young and Jae-han at their midpoint — the trust between them built entirely through radio transmissions across 26 years.

February 19, 2016

The full story of Cha Soo-hyun's connection to the cold cases — her own loss and her decades of investigation.

February 19, 2016

The institutional cover-up that has kept certain cases unsolved — who benefits from them staying cold.

February 26, 2016

Jae-han's disappearance from the historical record — and what it means for Hae-young's present.

February 26, 2016

The full story of how the walkie-talkie connects the two timelines — and why it chose these two men.

March 4, 2016

The case that directly connects to the Hwaseong murders — the drama's most historically weighty episode.

March 4, 2016

Jae-han's last transmission — what he tells Hae-young, knowing what is coming.

March 11, 2016

The drama's most agonising episode — attempting to change an outcome the past has already recorded.

March 11, 2016

The finale. Jo Jin-woong's performance as a detective whose sacrifice happens 26 years before anyone can thank him for it — one of the most emotionally devastating conclusions in Korean drama history.