Doctor Detective

Do Jun-eun, a genius epidemiologist, had her medical license suspended after an incident and now earns a living by helping cover up workplace injuries. UDC (Undiagnosed Disease Center) Director Gong Il-soon recruits Jun-eun to the UDC, but she refuses to open up. ©SBS

Before she can say goodbye, Haran's body is taken away by TL Group. Jun-eun entrusts the case to UDC's Ho Min-gi and heads to the office where Haran worked. The media reports Haran's death as self-inflicted due to alcohol poisoning. Suspecting Haran was poisoned by hazardous substances, Jun-eun teams up with Min-gi to obtain a plastic water bottle as evidence disproving the alcohol theory.©SBS

Mingi, convinced Joon-woong's UDC employment is confirmed and he'll be promoted to team leader, is in high spirits alone. Amidst the grief, Haran's funeral takes place, but her colleague Do-hyun is still missing. Meanwhile, a case involving a baker's asthma lands at UDC. Learning Jun-eun is team leader, Min-gi declares he'll quit. Il-sun tries to persuade him, bringing up his father.©SBS

Joon-woon, targeted by someone, suspects Tae-yong's involvement, but there was clearly another perpetrator present who wasn't part of his group. Released from custody, Min-gi throws himself into investigating the bakery. That night, Joon-woon receives a mysterious phone call. Min-gi discovers asthma-inducing substances at his side job at the furniture factory.©SBS

Jun-eun is rescued by Tae-yeon at the last moment and rushed to the hospital. Learning Mo Seong-guk, head of TL Oshim, is behind Jun-eun's attack, Tae-yeon storms into Oshim to warn him, but Seong-guk retorts it was Chairman Chee-gon's order. To clear Do-hyun's suspicion, Joon-eun searches for mercury evidence and detects it in hair found at Harang's home.©SBS

Jun-eun is troubled by Tae-yong's request to leak the Nam-il site information to the press in exchange for inside information. Barred from the field, Jun-eun secretly plans a strategy with Min-gi, successfully obtaining proof that Do-hyun suffered mercury poisoning. Concluding mercury poisoning was TL Metro's responsibility, UDC members raise a celebratory toast.©SBS

As patients flood into UDC, Mingi witnesses an accident involving an elderly man. The man's granddaughter, Hemi, presents Mingi with a portrait as a token of gratitude for his treatment. Taeyong, seeking to bring down Songkuk, attempts to exploit a national audit. Enraged, Gong orders Taeyong to travel to China. ©SBS

Coincidentally admitted to the same hospital, Gon and Haemi both survive, but Haemi loses her sight and shows signs of delirium, suggesting possible poisoning. Meanwhile, Min, told Gon's symptoms resemble those of a toxic gas victim, suspects Joon-woong. Il-sun pleads with Song-guk to revoke the suspension of search warrants, but Song-guk remains unmoved.©SBS

Il-sun severely reprimands the agents who went ahead with the search without authorization, but Min-gi rebels against such Il-sun. Realizing that workers, not the organization, must be protected, Il-sun orders the investigation resumed. Jun-woong and Min-gi infiltrate the factory disguised as short-term workers. ©SBS

As TL's pressure on UDC intensifies, Gon orders Jun-eun to investigate the sender of the threatening letter. Learning the sender is likely a work accident victim and that Sol-in's hair was enclosed, Jun-eun requests Il-sun's cooperation. The entire UDC team searches for the blackmailer. ©SBS

Yongduk was found dead alone in an abandoned factory. His body showed widespread symptoms of mercury poisoning, and it was revealed he had previously run a subcontracting company for TL displays. Meanwhile, at TL, Taeyong gathers the board members and declares they will settle past wrongdoings. ©SBS

Infiltrating the street dwellers' hideout, Mingi obtains information suggesting Yeon-duk may have been murdered. At TL, Tae-yong, having secured the support of numerous directors, is triumphantly appointed Vice Chairman, his ambition burning to finally steer TL according to his own will. ©SBS

UDC launched an epidemiological investigation at TL Medical Center to determine the cause of respiratory diseases. However, the investigation faced difficulties due to a lack of cooperation from parents, which is essential for environmental factor research. Meanwhile, Professor Hong of TL Medical Center announced that 90% of patients were infected with the Mongolian virus.©SBS

Suspecting toxic substances weren't limited to humidifier disinfectants, Jun-woong requests Tae-yong to search TL Chemical's premises. Tae-yong demands credit for the discovery as a condition, leading to the first investigation into the TL Group. UDC decodes the hidden message in the threatening letter and successfully identifies the toxic substance.©SBS

Joon-woong goes to Tae-yong's office to search for documents he left behind and discovers numerous pieces of evidence Song-kook had hidden away in the safe. Meanwhile, learning So-rin has been absent from kindergarten for a week, Joon-woong asks Il-soon to protect her.©SBS

Jun-woong presses Song-kook to reveal So-rin's whereabouts. Just then, a message arrives from Min, instructing him to go to the Nam-il site. So-rin is safely rescued, and Song-kook finally stands trial, but he denies the charges, claiming he only fulfilled his duty. One year after Song-guk's trial.©SBS