Cast
Ji Sung as Jang Jae-kyung, a detective of the Narcotics Team at Anhyeon Police Station
Jeon Mi-do as Oh Yun-jin, a social affairs reporter of the Anhyeon Economic Daily
Kwon Yul as Park Tae-jin, a prosecutor at Ahn Hyun District Office
Kim Kyung-nam as Won Jong-soo, Geumhyeong Group's successor
Yoon Na-moo as Park Jun-seo, the central figure in the incident
Jung Yoo-min as Choi Ji-yeon, Jun-seo's wife
Jung Jae-kwang as Kim Chang-soo, Jae-kyung's teammate
Cha Yup as Oh Chi-hyun, Jong-soo's chief secretary
Jeong Soon-won as Heo Joo-song, CEO of Two Star Holdings, an insurance company
Park Geun-rok as Jung Sang-ui, a researcher at Geumhyeong Pharmaceutical
Jun-seo's suicide occurred less than a month after taking out a life insurance policy, and since it had been less than two years since he enrolled, no payout would be made. Yun-jin suggests to Jun-seo’s wife, Choi Ji-yeon, that Jun-seo would never take his own life and that they should request an autopsy. If the autopsy concludes it was a homicide, Jae-kyung and Yun-jin could receive a significant insurance payout. This makes it seem like Jae-kyung’s insistence on an autopsy is driven by financial motives rather than pure intentions.
In reality, Jun-seo's will included not just Jae-kyung and Yun-jin but also a man named Lee Myung-guk. Jae-kyung receives Lee Myung-guk’s personal information from Joo-song. Tae-jin, who is both Jae-kyung's high school friend and a prosecutor at the Anhyeon District Office, tries to prevent the autopsy. However, Jun-seo's wife, Ji-yeon, decides to go ahead with it, as she cannot believe Jun-seo would commit suicide. Jong-soo, angered by Tae-jin's failure to stop the autopsy, reveals that the vice president of Geumhyeong Group holds more power than a prosecutor.
Jae-kyung begins investigating the drug that caused his addiction. His investigation reveals that the drug was recently popular but is no longer available. He also looks into Lee Myung-guk and discovers that he had terminal lung cancer and went missing before he could share something with Yun-jin. Could Jun-seo have wanted Jae-kyung to investigate Lee Myung-guk through his death?
Meanwhile, Yun-jin conducts her investigation into Jun-seo's death and finds Jae-kyung collapsed from drug withdrawal. She helps him home, where they find the drugs. They clash as Jae-kyung tries to retrieve them.
Later that night, Jae-kyung confides in Yun-jin about his addiction. Yun-jin then shares what she knows about Lee Myung-guk, and they head to his house together. There, they find Lee Myung-guk's body, sealed to prevent the smell from escaping. The body, which has been dead for seven months, leaks a lot of fluid, indicating it had been frozen and only recently moved to the house. Suddenly, the house catches fire, destroying the evidence.
As the episode ends, Jae-kyung's withdrawal symptoms return, and he tries to get his hands on the drugs seized by the police. This cliffhanger wraps up episode 3 of Connection.
