When the Past Can Still Be Changed
Park Hae-young is a criminal profiler in 2015 who discovers a mysterious walkie-talkie that connects him to Detective Lee Jae-han — a principled, stubborn cop living in 1989. Through this impossible connection, the two men begin solving cold cases together, changing the past and the present in ways both miraculous and devastating. Every time they save a life, the timeline shifts. Every victory has consequences. And the deeper they go, the more they realize that the serial killer they are hunting may be someone neither of them suspects.
Signal is not just a crime thriller — it is a philosophical exploration of justice, sacrifice, and whether the past should be changed at all. Inspired by real Korean cold cases including the Hwaseong serial murders, it weaves true crime with supernatural elements to create something entirely unique. Ten years after its release, Signal remains widely considered the greatest K-drama ever made, a perfect blend of gripping storytelling, emotional depth, and social commentary.
Lee Je-hoon and Cho Jin-woong: A Legendary Duo
Lee Je-hoon delivers his career-best performance as Park Hae-young, a man haunted by a past he cannot change. Cho Jin-woong is extraordinary as Lee Jae-han, bringing warmth, humor, and devastating tragedy to a character who exists mostly through a crackling radio speaker. Their chemistry — despite being separated by decades — is the emotional core of the series. Kim Hye-soo rounds out the cast as Cha Soo-hyun, a detective who connects both timelines and carries the weight of loving someone she can never truly reach.
Frequently Asked Questions
Is Signal based on a true story?
Signal draws heavy inspiration from real Korean cold cases, most notably the Hwaseong serial murders that remained unsolved for 30 years. Several cases in the drama are based on actual crimes that were eventually solved with modern DNA technology.
Will there be Signal Season 2?
Signal Season 2 has been officially confirmed and is expected to air in 2025-2026 with the original cast returning. The announcement broke Korean entertainment news worldwide.
Where can I watch Signal?
Signal is available on Netflix and Viki worldwide with subtitles in multiple languages.