Signal (South Korean TV series)

Signal (Korean: 시그널) is a South Korean television series written by Kim Eun-hee, directed by Kim Won-seok, and starring Lee Je-hoon, Kim Hye-soo, and Cho Jin-woong. Inspired by real-life criminal incidents in Korea, including the Hwaseong serial murders. The first season aired on tvN from January 22 to March 12, 2016, every Friday and Saturday at 20:30 (KST). In March 2024, a second season was confirmed in production.

The series received widespread acclaim from audiences and critics alike for its story and performances. It is also one of the highest-rated Korean dramas in cable television history with a peak audience viewership of 12.544%.

Plot

In present-day 2015, criminal profiler Park Hae-young (Lee Je-hoon) finds a mysterious discarded walkie talkie; inexplicably, the person at the other end, Detective Jae-han (Cho Jin-woong), is from the past, and addresses him familiarly, even though Hae-young has never met him. Hae-young is able to solve a 15-year-old kidnapping and murder case involving a former classmate from his childhood with Jae-han's help. The success of this case triggers the formation of a cold case team, led by Detective Cha Soo-hyun (Kim Hye-soo), who has been searching for Jae-han, her long-lost mentor and unrequited love, for the past 15 years.

With Jae-han's help from the 1990s, Hae-young solves other cold cases that have remained unsolved for years and is drawn into the mystery surrounding Jae-han's disappearance in the year 2000. As they try to fix the past and catch the criminals, unintended consequences follow in the present.

Cast

Main

Lee Je-hoon as Park Hae-young

The jaded and hotheaded criminal profiler who finds the walkie-talkie by chance, and uses his connection with Jae-han to solve cold cases.

Kim Hye-soo as Cha Soo-hyun

The first female police officer in the Special Task Force, she becomes the leader of the Seoul cold case squad. She has been searching for Jae-han, her mentor and unrequited love, for 15 years, believing him to be dead.

Cho Jin-woong as Lee Jae-han

The socially inept but virtuous and quick-tempered detective from the past who establishes a rapport with Park through the walkie-talkie. His timeline during his communication with Park spans from 1989 to 2000.

Supporting

Police officers

Jang Hyun-sung as Kim Bum-joo

The corrupt police superintendent.

Jung Hae-kyun as Ahn Chi-soo

The section chief and supervisor of the Seoul cold case squad who acts as Bum-joo's lackey but appears morally gray.

Kim Won-hae as Kim Gye-chul

A police officer who joins the Seoul cold case squad and often serves as comic relief.

Jung Han-bi as Oh Yoon-seo

A colonel.

Lee Yoo-jun as Jung Han-ki

A forensic scientist and member of the Seoul cold case squad, often seen with Detective Kim.

Kim Min-kyu as Hwang Eui-kyung

A junior officer that cleans up the Seoul cold case squad's work area and admires them.

Extended

Kim Hyun-bin as young Park Hae-young
Kang Chan-hee as Park Sun-woo

Hae-young's older brother who was convicted in the high school gang rape case and died by suicide after being released.

Yang Dae-hyuk as Hong Won-seo

A detective.

Lee Moon-soo as Lee Jae-han's father
Seo Ju-hee as Cha Soo-hyun's mother
Lim Hwa-young as Cha Soo-hyun's younger sister
Lee Do-yeop as Kim Jung-jae

Special appearances

Episodes

Original soundtrack

Reception

Upon its premiere, the series attracted attention for weaving actual cases into its plot and attained high ratings. With its finale rating of 12.54%, it is one of the highest rated Korean dramas in cable television history. It received praise for its solid acting, tightly-constructed plot and detailed and sophisticated direction; and enjoyed success internationally in China and Japan.

The drama went on to win several awards from different award-giving bodies, including Best Drama, Best Screenplay for Kim Eun-hee, and Best Actress for Kim Hye-soo at the 52nd Baeksang Arts Awards, as well as another Best Actress award for Kim and the Daesang (Grand Prize for Television) for Cho Jin-woong at the tvN10 Awards. Cho also won the Daesang at the 1st Asia Artist Awards for his performance.

Ratings

Awards and nominations

Adaptations

A Japanese remake of the series starring Kentaro Sakaguchi was aired from April 10 to June 12, 2018, on Fuji TV.
On October 23, 2019, Unknown Number, a Chinese remake of the series, started airing on Tencent Video.
On January 20, 2023, a Thai remake of the series titled 23:23, was aired on True4U.
On April 24, 2024, an Indian remake of the series titled Gyaarah Gyaarah, has premiered on August 9, 2024 on Zee5.