Original: 낮과 밤
While unraveling an enigmatic murder mystery, a special force leader realizes this case is related to the incident that took 28 years ago in a small town.
Jung Woo and his team have been investigating a serial bank robbery case for months, but they’re told to dig into the so-called forewarned murder case. Unwillingly, they go to a club where the forewarned victim is supposed to be. There, they witness a strange suicide case.
Jung Woo decodes the messages that the murderer sent and finds a lead. Jamie joins the team to solve the forewarned murder case, but the team members are hostile toward her. She figures out one common factor among the victims- they were all smiling the moment they died.
Jamie finds Jung Woo suspicious as he seems to be hiding a secret. Despite the events that make Jung Woo suspicious, Hye Won puts her full trust in Jung Woo. Another forewarning arrives, and the victim is said to be Son Min Ho, the former leader of White Night Village.
Jung Woo and Jamie find out that they’re both from White Night Village. Jung Woo acts like White Night Village has nothing to do with the forewarned murder cases, but Jamie thinks differently. Meanwhile, a fire breaks out in the villa where Son Min Ho is residing.
Jung Woo saves the people who were trapped in the fire and instantly becomes a national hero. Jamie wakes up in the hospital and she’s about the receive treatment by force. Meanwhile, Ji Wook provides an important piece of evidence that proves the culprit is one of the members of Special Team.
Ji Wook realizes Son Min Ho is in danger, so he tries to escape from the safehouse with him. However, Jung Woo stops them and attacks Son Min Ho. Jung Woo gets arrested, and he pleads guilty. Meanwhile, Jamie finds out Jung Woo was the one who helped her get surgery, but she can’t figure out why.
Everyone including Hye Won is shocked by the fact that Jung Woo is the culprit of the forewarned murder cases. And those who know the truth behind White Night Village are going after Jung Woo. Meanwhile, Ji Wook receives a flash drive from an anonymous informant.
The truth behind the forewarning murders starts to come up to the surface. Jamie and Hye Won keep following the evidence related to what happened in White Night Village 28 years ago. Meanwhile, Jung Woo who has found out the experiments are still being conducted in a secret lab goes to visit the foundation himself.
Jung Woo continues to search for the secret lab. He runs into kids at an orphanage who talk about several kids being adopted by new families at the same time. Jung Woo thinks there’s something fishy going on in that facility. Meanwhile, Jamie happens to see a man who seems to have collapsed on the street. Without knowing his identity, she takes him to the police station.
Jung Woo witnesses that a group of children is forced to get in a black van in front of Seoul Hangang Welfare Center and taken to somewhere, and he starts to follow the van. At the same time, Hye Won, who’s suspicious of his father, keeps tailing him. Meanwhile, Lee Tae Soo jumps off his office building when Jamie and her colleagues visit there.
Hye Won manages to save Jung Woo from the attack and car accident. They soon find out that one of their colleagues has betrayed them. Meanwhile, Jamie sets off for White Night Village with Ji Wook to recollect her memories of what happened in the village. But then, a new warning arrives at Ji Wook’s office.
Jamie finally arrives at the very place she abhors to even stay for a second. At the White Night Village, she and Ji Wook search for clues that might trigger Jamie’s lost memories. Meanwhile, Jung Woo is able to secure Oh Jung Hwan’s son. Later that night, when Jamie and Ji Wook find themselves isolated at the village, a group of gang ambushes them. Standing in front of Jamie when she recovers from unconsciousness are Jung Woo and Jae Woong.
Jamie realizes that Jung Woo is her twin brother, the so-called monster who saved her life. After saving Jamie, Jung Woo continues with the investigation to find the location of the secret lab. Meanwhile, Hye Won persuades her dad to step away from the unethical experiment. However, Il Do chooses his life’s work over his daughter.
Hye Won gets abducted and held hostage. Jung Woo finally finds the secret lab and goes inside. But there’s someone who’s watching him in the building. Meanwhile, Jae Woong tells Yong Shik who the next target is. Yong Shik makes a call to somebody to make him prepared for Jae Woong’s attack.
Jung Woo tells Jamie that he has finally met Hyun Hee who is known to be Jung Woo and Jamie’s mother. After hearing that, Jamie seems to feel down. Meanwhile, Hye Won asks her father about the location of the secret lab again, but he refuses to share it. Hye Won tells her father that she has seen the formula known to have been erased by Jung Woo.
After finding out who the president is, Jung Woo attempts to find the location of the secret lab by using Oh Jung Hwan as bait. Hyun Hee realizes that something is off and tries to lure in Jung Woo. With only few seconds left before the bomb goes off, Jung Woo has to make a decision whether to leave his mother to die or to save her. The last battle against White Night Foundation begins.
