Signal

Cinematography

• 
  Choi Sang Mook
• 
  Lee Joo Young

Composer

• 
  Copykumo
• 
  Jung Se Rin

Director

• 
  Kim Won Suk

Editor

• 
  Kim Na Young

Screenwriter

• 
  Kim Eun Hee

Main Role

• 
  Lee Je Hoon

  Park Hae Yeong

  Main Role
• 
  Kim Hye Soo

  Cha Su Hyeon

  Main Role
• 
  Jo Jin Woong

  Lee Jae Han

  Main Role

Support Role

• 
  Kim Won Hae

  Kim Gye Cheol [Cold case team]

  Support Role
• 
  Lee Yoo Joon

  Jung Heon Gi [Forensic investigator]

  Support Role
• 
  Jang Hyun Sung

  Kim Beom Ju [Police chief]

  Support Role
• 
  Jung Hae Kyun

  An Chi Su

  Support Role
• 
  Jung Han Bi

  O Yun Seo

  Support Role
• 
  Kim Min Gue

  Hwang Ui Gyeong

  Support Role
• 
  Chani

  Park Seon U

  Support Role
• 
  Lee Moon Soo

  [Jae Han's father]

  Support Role
• 
  Hwang Tae Kwang

  Kim Jeong Je [Past detective]

  Support Role
• 
  Eom Ji Man

  Kim Hae Cheol [Past detective]

  Support Role
• 
  Son Hyun Joo

  Jung Yeong Cheol [Congressman]

  Support Role
• 
  Im Hwa Young

  Cha Su Min [Su Hyeon's younger sister]

  Support Role
• 
  Joo Myung Chul

  Kim Seong Beom [Loan shark]

  Support Role
• 
  Jin Woo Jin

  Jang Gi Ju

  Support Role
• 
  Hyeon Jik

  Ko Jin U

  Support Role
• 
  Seo Dong Gap

  Detective Moon

  Support Role
• 
  Jung Gi Sub

  Choi Seok Won [Past criminal detective]

  Support Role
• 
  Jang Nam Boo

  Detective Kang

  Support Role

Guest Role

• 
  Lee Chung Hee

  [Nurse] (Ep. 1)

  Guest Role
• 
  Lee Young Eun

  Kim Yun Jeong (Ep. 1-2)

  Guest Role
• 
  Oh Yeon Ah

  Yun Su A [Nurse] (Ep. 1-2)

  Guest Role
• 
  Song Yoo Hyun

  Kang Se Yeong [Nurse] (Ep. 1-2)

  Guest Role
• 
  Seo Jung Joon

  Seo Hyeong Jun [Prime suspect in the kidnapping case] (Ep. 1-2)

  Guest Role
• 
  Choi Hyun Joon

  [Detective] (Ep. 1-2)

  Guest Role
• 
  Kim Soo Jin

  [Yun Jeong's mother] (Ep. 1-2)

  Guest Role
• 
  Jang Hyuk Jin

  [Celebrity news journalist] (Ep. 1-2)

  Guest Role
• 
  Yoon Ji In

  Jung Gyeong Sun [Young] (Ep. 1-4)

  Guest Role
• 
  Im Jae Geun

  [Yun So’s assistant] (Ep. 1, 5)

  Guest Role
• 
  Kim Kwang Sub

  [Bully student] (Ep. 1, 13)

  Guest Role
• 
  Jung Jong Yul

  [Police sergeant] (Ep. 1, 16)

  Guest Role
• 
  Min Dae Shik

  [PR police officer] (Ep. 2)

  Guest Role
• 
  Choi Dae Woong

  [Grandfather witness] (Ep. 2)

  Guest Role
• 
  Keum Dong Hyun

  [News programme guest] (Ep. 2)

  Guest Role
• 
  Seo Myung Chan

  [News programme guest] (Ep. 2)

  Guest Role
• 
  Moon Young Dong

  Kim Chang Su (Ep. 2-3)

  Guest Role
• 
  Nam Sang Ran

  Hwang Min Ju (Ep. 2-4)

  Guest Role
• 
  Yoon Byung Hee

  Choi Yeong Sin (Ep. 2-4)

  Guest Role
• 
  Sung Hyun Mi

  Jung Gyeong Sun (Ep. 2-4)

  Guest Role
• 
  Kim Gi Cheon

  Lee Chan Gu [Bus driver] (Ep. 2-4)

  Guest Role
• 
  Lee Ki Sub

  Lee Jin Hyeong [Chan Gu's son] (Ep. 2-4)

  Guest Role
• 
  Lee Shi A

  Kim Won Gyeong [Jae Han's crush] (Ep. 2-4)

  Guest Role
• 
  Kim Jung Young

  [Won Gyeong's aunt] (Ep. 2-5)

  Guest Role
• 
  Lee Do Yeop

  Detective Park (Ep. 3-4)

  Guest Role
• 
  Lim Wook Jin

  [Detective] (Ep. 3-4)

  Guest Role
• 
  Tak Sung Eun

  [Mi Sun's daughter] (Ep. 3-4)

  Guest Role
• 
  Hong Suk Bin

  [Mi Sun's husband] (Ep. 3-4, 13)

  Guest Role
• 
  Won Geun Hee

  [Bus driver] (Ep. 4)

  Guest Role
• 
  Oh Jin Ha

  [Sehoon hospital nurse] (Ep. 4)

  Guest Role
• 
  Lee Sang Hwa

  [Room salon owner] (Ep. 5)

  Guest Role
• 
  Kim Myung Joong

  [Prison guard] (Ep. 5-6)

  Guest Role
• 
  Kang Joo Hee

  [Dong Hun's wife] (Ep. 5-6)

  Guest Role
• 
  Jung Suk Yong

  O Gyeong Tae [Eun Ji's father] (Ep. 5-7)

  Guest Role
• 
  Park Si Eun

  O Eun Ji [Gyeong Tae's daughter] (Ep. 5-7)

  Guest Role
• 
  Yoo Ha Bok

  Sin Dong Hun [Yeo Jin's father] (Ep. 5-7)

  Guest Role
• 
  Choi Woo Ri

  Sin Yeo Jin [Bridge collapse survivor] (Ep. 5-7)

  Guest Role
• 
  Kim Jong Goo

  Kim Jung Seong [Past detective squad chief] (Ep. 5-7)

  Guest Role
• 
  Seon Yul U

  [Detective] (Ep. 6)

  Guest Role
• 
  Kim Sang Il

  [Detective] (Ep. 6)

  Guest Role
• 
  Park Jin Soo

  [Jinseong Bank employee] (Ep. 6)

  Guest Role
• 
  Park Jung Min

  [Se Gyu's chauffeur] (Ep. 6-7)

  Guest Role
• 
  Ahn Soo Ho

  [Vacation home caretaker] (Ep. 6-7)

  Guest Role
• 
  Im Chul Soo

  [Informant] (Ep. 6-7, 9)

  Guest Role
• 
  Lee Dong Ha

  Han Se Gyu [Lawyer / Witnesses of the bridge incident] (Ep. 6-8)

  Guest Role
• 
  Oh Ki Hwan

  [Detective] (Ep. 6, 13, 15)

  Guest Role
• 
  Yoon Bok Sung

  [Attorney] (Ep. 7)

  Guest Role
• 
  Park Ji Yun

  [Café waitress] (Ep. 7)

  Guest Role
• 
  Yang Eun Yong

  Sin Jeong Hye (Ep. 7-8)

  Guest Role
• 
  Kim Hyun Sung

  Kim Min Seong [Da Hye's fiancé] (Ep. 7-8)

  Guest Role
• 
  Lee Na Ra

  Sin Da Hye [Holder of the stolen necklace] (Ep. 7-8)

  Guest Role
• 
  Jung Byung Ho

  [Jeweler] (Ep. 7-8)

  Guest Role
• 
  Sun Hak

  [Aide] (Ep. 7-16)

  Guest Role
• 
  Kim Ryeo Eun

  Kim Ji Hui (Ep. 8)

  Guest Role
• 
  Ri Min

  Gwang Jae (Ep. 8)

  Guest Role
• 
  Yoo Jae Ik

  O Seung Jun [Investigator] (Ep. 8)

  Guest Role
• 
  Kim Yun Hui

  Yun Sang Mi (Ep. 9)

  Guest Role
• 
  Park Sung Hoon

  Detective Jung (Ep. 9)

  Guest Role
• 
  Yang Seung Kul

  [Street cleaner] (Ep. 9)

  Guest Role
• 
  Im Yong Soon

  [Workshop owner] (Ep. 9)

  Guest Role
• 
  Kim Sa Hun

  [Hiker] (Ep. 9)

  Guest Role
• 
  Lee Seung Chul

  [Homeless man] (Ep. 9)

  Guest Role
• 
  Yang Dae Hyuk

  [Heungwon detective] (Ep. 9)

  Guest Role
• 
  Kim Gyeong Min

  [Yeong Jin's husband] (Ep. 9)

  Guest Role
• 
  Kim Ga Young

  [Ticket booth employee] (Ep. 9)

  Guest Role
• 
  Bong Eun Sun

  Joo In Hui (Ep. 9-10)

  Guest Role
• 
  Lee Sang Yeob

  Kim Jin U [Serial killer] (Ep. 9-11)

  Guest Role
• 
  Seo Eun Ah

  Yoo Seung Yeon [Girl who liked Jin Woo] (Ep. 9-11)

  Guest Role
• 
  Lee Chae Kyung

  [Jin U's mother] (Ep. 10)

  Guest Role
• 
  Song Kyung Hwa

  [Convenience store owner] (Ep. 10)

  Guest Role
• 
  Kim Hye Ran

  [Sekang Electric Bulb employee] (Ep. 10)

  Guest Role
• 
  Lee Il Seop

  Park Gang Ho [Police chief] (Ep. 10)

  Guest Role
• 
  Kim Dae Yoon

  [Cashier] (Ep. 10-11)

  Guest Role
• 
  Lee Sun Young

  [Girl #1] (Ep. 11)

  Guest Role
• 
  Ji Hye In

  [Girl #3] (Ep. 11)

  Guest Role
• 
  Kim Jeong Woo

  [Womanizer] (Ep. 11)

  Guest Role
• 
  Jang Yong Bok

  [Congressman] (Ep. 11)

  Guest Role
• 
  Park Eun Young

  [Student's mother] (Ep. 11)

  Guest Role
• 
  Kim Hak Seon

  Park Myeong Hun (Ep. 11-12)

  Guest Role
• 
  Jung Hyun Seok

  [Doctor] (Ep. 11-12)

  Guest Role
• 
  Lee Dong Hee

  [Farmer] (Ep. 11-12)

  Guest Role
• 
  Hong Boo Hyang

  [Farmer's wife] (Ep. 11-12)

  Guest Role
• 
  Lee Dal

  [School bully] (Ep. 11-12, 14)

  Guest Role
• 
  Jeon Soo Ji

  Kang Hye Seung (Ep. 11-16)

  Guest Role
• 
  Shin Yi Joon

  Kang Hye Seung [Young] (Ep. 11-16)

  Guest Role
• 
  Kim Woo Seok

  Lee Dong Jin [Rape case perpetrator] (Ep. 11-16)

  Guest Role
• 
  Park Young Hoon

  Min Ho (Ep. 12)

  Guest Role
• 
  In Sung Ho

  [Dong Jin's father] (Ep. 12)

  Guest Role
• 
  Maeng Bong Hak

  [Dean of students] (Ep. 12)

  Guest Role
• 
  Lee Jin Kwon

  [Bully] (Ep. 12-13)

  Guest Role
• 
  Sung Ki Yoon

  [Hae Yeong's father] (Ep. 12, 14, 16)

  Guest Role
• 
  Hwang Seung Eon

  Han Do Yeon (Ep. 13)

  Guest Role
• 
  Lee Joong Yul

  [Restaurant customer] (Ep. 13)

  Guest Role
• 
  Lee Jae Eun

  [Market stall owner] (Ep. 13)

  Guest Role
• 
  Kang Chan Yang

  [Woman going to work] (Ep. 13)

  Guest Role
• 
  Yoo Yong Beom

  [Detective] (Ep. 13-14)

  Guest Role
• 
  Jung Young Joo

  [Restaurant owner] (Ep. 13, 16)

  Guest Role
• 
  Seo Ji Hoon

  Jang Tae Jin [Rape case perpetrator] (Ep. 14)

  Guest Role
• 
  Shin Moon Sung

  [Detective] (Ep. 14)

  Guest Role
• 
  Jung Jong Woo

  [Injoo detective] (Ep. 14)

  Guest Role
• 
  Jun Joon Woo

  [Police officer] (Ep. 15)

  Guest Role
• 
  Choi Young In

  [Injoo Hospital janitor] (Ep. 15)

  Guest Role
• 
  Son Yeong Soon

  [Elderly recycler] (Ep. 16)

  Guest Role
• 
  Kang Ji Won

  Sin Yeo Jin [Child]

  Guest Role
• 
  Ahn Eun Ho

  Park Hae Yeong [Teen]

  Guest Role
• 
  Kim Hyeon Bin

  Park Hae Yeong [Child]

  Guest Role
• 
  Kang Pil Sun

  [Reporter]

  Guest Role
• 
  Kim Dae Hyun

  [Detective]

  Guest Role
• 
  Kang Soo Jin

  [News anchor]

  Guest Role
• 
  Oh Jin Seok

  [Prison officer]

  Guest Role
• 
  Kim Geun Yeong

  [Da Hye's mother]

  Guest Role
• 
  Son Kyung Won

  [Hye Seung's father]

  Guest Role
• 
  Seo Joo Hee

  [Su Hyeon's mother]

  Guest Role
• 
  Song Ji Woo

  [Su Hyeon's nephew]

  Guest Role
• 
  Ahn Jung Woo

  [Su Hyeon's nephew]

  Guest Role
• 
  Ahn Hyun Jung

  [Hae Yeong's mother]

  Guest Role
• 
  Seol Chang Hee

  [Jinyang district reporter #1]

  Guest Role
• 
  Ham Jin Sung

  [Gyeonggi province detective]

  Guest Role
• 
  Jung Tae Ya Guest Role
• 
  Jung Je Woo Guest Role
• 
  Kim Oh Bok Guest Role
• 
  Cha Seung Ho Guest Role
• 
  Kim Chan Yi Guest Role

Unknown

• 
  Kim Jung Seok Unknown