One of the bodies entrusted to Seo Se-hyun, a promising soup autopsy. The thread sutured with the smell of rocks in the body reminds me of her past. Jung-hyun, the head of the strong team, is in charge of the investigation.
Se-hyun, who visited the body organic field with Chung-hyun, recalls the traces of his dead murderer, Yoon Jo-kyun. Meanwhile, after visiting Yongcheon site, Oh Min-ho, the team member of Se-hyun, continues the absence for a few days.
In Yongcheon, a carcass with a thread is found, and the identity of the body is found to be the missing team of Se-hyun. Se-hyun, who discovered the same technique and clues in the second body, feels that the bacteria are back.
Chung-hyun, who arrested an innocent citizen as a suspect, is hit by the media, and Se-hyun, who helps him, announces a serial murder. Se-hyun, who reveals his existence to Cho-kyun, tries to stimulate him and pull him over the surface.
Se-hyun finds his childhood photographs planted by Cho-kyun in the third body and is shocked. Se-hyun, who is in a hurry by the caught clue, heads to Hae-ryong, who lived with Jo-kyun in the past.
Jung-hyun's investigation expands to the "Cheongwoon Port Incident", where Se-hyun and Cho-kyun were together. In the investigation situation, Se-hyun suggests that Cho-kyun is making a fake criminal.
Se-hyun, who managed to deal with the trap of Cho-kyun, meets Jocyun at the appointment. On the other hand, Jung-hyun finds out that Se-hyun hid the outcome of the drug and doubts.
Se-hyun is a suspect of all murder in Cho-kyun's careful manipulation, and even Hyun-hyun pursues Se-hyun. Se-hyun, who is at a corner, heads to a nursing hospital with a mother-in-law, and finds the situation where Cho-kyun went there.
After reaching the truth through the living victims, Jung-hyun tracks the tower of Cho-kyun. Se-hyun, who plans to escape from the tower car, takes Se-eun to escape.
Se-eun's whereabouts are strange, and Se-hyun believes that Cho-kyun has already killed her and is in anger. Se-hyun, who received the message of Cho-kyun, leaves the hospital with a determination to kill Cho-kyun, and hyun leaves Se-eun.
Se-hyun faces Jo-kyun in the tidal flats and stands in front of the last choice. At the same time, Jung-hyun, who received a rescue signal, finds the whereabouts of Se-eun.
