In the riveting third episode of the Korean drama "Connection," the plot thickens as secrets about inheritance and a mysterious drug take center stage. Oh Yun-jin is shocked to discover she's the beneficiary and heir to Park Joon-woo's life insurance, leading her to advocate for an autopsy to uncover the truth. On the other side, Won Jong Soo is furious with Park Jun Seo for the late disclosure of the will, questioning the rationale behind leaving the insurance money to two relatively unfamiliar individuals and facing the disdain of their peers, which only strengthens his opposition to the autopsy.
A contentious debate over the autopsy ensues between Jang Jae-kyeong and Park Jun Seo. The situation escalates when the police get involved, with Park Jun Seo suggesting that Jang Jae-kyeong and Oh Yun-jin are pushing for the autopsy to secure the insurance payout. This accusation leads Park Joon-woo's wife to feel her husband is being exploited, causing her to break down. Ultimately, Jang Jae-kyeong, Oh Yun-jin, and Xu Zhousong are all brought in for questioning. The police understand they lack a motive for murder, as claiming the insurance money would necessitate staging it as a homicide rather than a suicide. Despite this, the reason for the bequest remains enigmatic. Park Jun Seo insists there's no evidence of foul play, advocating against the autopsy, but Jang Jae-kyeong is convinced that an autopsy would reveal something they're desperate to conceal. Eventually, Park Joon-woo's wife decides to proceed with the autopsy to find closure and dispel any doubts.
The autopsy results are expected to take at least a month. In the meantime, Jang Jae-kyeong remains at the police station, investigating a fight between two young people under the influence, which occurred in the early hours of February 27, 2024. He finds that the drug involved has been difficult to obtain for the past two weeks. Digging deeper, Jang Jae-kyeong learns that Lee Minguk, missing for seven months and suffering from terminal lung cancer, was thought to have made an extreme choice due to his illness. However, it's revealed that Lee Minguk had intended to expose corporate scandals to Oh Yun-jin but never showed up.
Jang Jae-kyeong acquires Lee Minguk's notebook and documents posthumously. Later, as he experiences withdrawal symptoms, Oh Yun-jin finds him and takes him home. Unexpectedly, they discover a package addressed to Park Joon-woo at Jang Jae-kyeong's residence, containing a 'new type of banned drug.' It becomes clear that Jang Jae-kyeong had consumed this drug, leading to his violent behavior and cravings.
Oh Yun-jin flushes the drug down the toilet. By evening, as Jang Jae-kyeong regains stability, he expresses regret for not forgiving Park Joon-woo in time and recounts his experience of being drugged. He is adamant that this secret must be kept from others; otherwise, if discovered, he would be removed from the case, and the investigation would lose momentum. Consequently, Oh Yun-jin decides to assist Jang Jae-kyeong and takes him to Lee Minguk's home to search for clues. To their surprise, they find out that the body and Lee Minguk are actually identities of a senior member of their club. Jang Jae-kyeong deduces that Lee Minguk must have been kept frozen for a long time and only recently thawed.
As they grapple with this revelation, their investigation is violently interrupted by an incendiary attack on the house, resulting in an inferno that consumes Lee Minguk's body and destroys all evidence within. The third episode of "Connection" leaves viewers on a cliffhanger, eager to uncover the truth behind the mysterious drug, the tangled relationships, and the relentless pursuit of justice in the face of adversity.