Season 1

Fate seems relentless for Dong-ju as he encounters a car accident and learns of his mother's DUI offense, further adding to his hardships. Like many others who reach rock bottom in real life, Dong-ju makes an unwise decision when he accidentally comes across the script of a novel belonging to the victim of his car accident. To his surprise, the novel achieves great success. However, the situation takes a turn when the boy Dong-ju hit finally regains consciousness.

Dong-ju's primary concern upon the boy regaining consciousness is whether his old memories have returned. Dong-ju is fully aware of his grave mistake and feels obligated to reveal the truth, regardless of whether he remembers anything or not. Simultaneously, as the murder cases and missing persons investigations progress, the similarities between them intensify, leading to a growing momentum. However, Dong-ju has no idea how this would affect him.

Hyun-soo suggests putting up a banner to look for Kang-san’s family. Kang-san gets discharged from the hospital and decides to stay at Dong-ju’s place. While inspecting the site of the accident, Kang-san sees a boy and follows him. Kang-san finds out that the boy has been abused by his mother. Meanwhile, Hyun-soo visits Dong-ju at his place and asks what motivated him to write the novel.

Hyun-soo tells Dong-ju that the murders in his novel are happening in real life. Dong-ju thinks Hyun-soo’s claim is outrageous, but he finds out that she is right. But Dong-ju doesn't report it to the police because he's afraid of losing the luxury he's enjoying. Meanwhile, Byung-man visits Assemblyman Byun and asks about the murder case from 27 years ago.

Dong-ju visits his old high school’s principal and sees a photo of a man who looks exactly like Ki-jeok. He asks around and finds out that the man in the photo is Lee Kang-san who went missing in 1995 with his brother, Lee Ha-neul. Meanwhile, Ki-jeok tells Dong-ju that his memories are coming back and that he remembers meeting Dong-ju’s father.

Dong-ju realizes the connection Ki-jeok has with his dad. No Young-nam kidnaps Assemblyman Byun’s daughter and demands the assemblyman to confess that he tortured him 27 years ago. Assemblyman Byun’s daughter coincidentally passes by Ki-jeok, and Ki-jeok realizes that she needs help. When Dong-ju faces No Young-nam, he asks Dong-ju to save him.

Dong-ju realizes that the videotape No Myung-nam mentioned could be important evidence, so he looks for it. Ki-jeok visits Woo-jung's cafe and sees the photo of Kang-san, which brings back some of his memories. Meanwhile, during Dong-ju’s book signing event, a mysterious man drops by and leaves him a note.

Ki-jeok calls Hyun-soo and asks her to find his family with his real name, Lee Kang-san. He then meets Woo-jung and asks her about his brother. During police interrogation, No Myung-nam has a panic attack and passes out. Meanwhile, Dong-ju finally meets Lee Tae-man and talks about his novel.

Kang-san persists in probing Dong-ju's awareness of his identity, raising tough questions about when and how he became aware. Although Dong-ju acknowledges his mistakes, he also believes that certain things are best left unspoken. As a result, he resorts to a convenient truth. Meanwhile, Dong-ju is confronted with plagiarism allegations concerning his best-selling novel, and he may have to shoulder the blame alone if things turn against him.

The discovery of skeletal remains and a student card with Lee Ha-neul's name at Sopyung Lake marks a significant shift in the investigation. Kang-san is heartbroken, fearing the loss of his brother. Meanwhile, Hye-kyung becomes suspicious of Tae-man's attention towards the boy living with Dong-ju. Acting as if she is unfamiliar with the boy, Hye-kyung accepts Kang-san's picture from Tae-man but immediately visits Dong-ju's house, bringing a mysterious gift.

Dong-joo and Kang-san stumble upon a flash drive inside a gift Hye-kyung left behind after her short visit. The data inside seems significant enough to shake the whole country. The two feel the need to be honest with each other if they are to work together toward the truth. Meanwhile at the station, the flash drive goes missing, and the last person who held on to it was Detective Kim. Kang-san's pursuit of his brother continues.

The police investigation intensifies as they start suspecting Byun Jong-il's involvement in the Jeon Doo-hyun murder case. Simultaneously, No Myung-nam is discovered in an alleged suicide attempt. Meanwhile, Kang-san confides all his secrets to Hyun-soo, who then seeks a favor from him. However, Dong-joo vehemently rejects the idea for Kang-san's well-being. On a hospital bed, Myung-nam remains unconscious, and Kang-san tries to read his troubled state of mind.

The discovery of skeletal remains and a student card with Lee Ha-neul's name at Sopyung Lake marks a significant shift in the investigation. Kang San is heartbroken, fearing the loss of his brother. Meanwhile, Hye-kyung becomes suspicious of Tae-man's attention towards the boy living with Dong-ju. Acting as if she is unfamiliar with the boy, Hye-kyung accepts Kang San's picture from Tae-man but immediately visits Dong-ju's house, bringing a mysterious gift.

As the police approach the truth, Lee Tae-man's discomfort grows, causing him to make rushed mistakes. Dong-ju uncovers news of Byun Jong-il's death and holds himself responsible for failing to elicit a confession regarding his father's murder. Meanwhile, Kang San finally meets his brother and comprehends why Ha-neul is adamant about keeping Kang San away. At the same time, Dong-ju has his own agenda to finalize things definitively.

Dong Ju drops a bombshell during a TV show, bringing to light all the concealed facts related to Lee Tae-man and others, including his own undisclosed matters. This disclosure causes a shift in the investigation, prompting individuals previously deemed unlikely to cooperate to come forward voluntarily for interrogation by the police. Meanwhile, an individual approaches Kang San with the demeanor of a guilty party, earnestly seeking forgiveness.

Kang San is regretful for losing control and causing harm to Dong-ju. Dong-ju reassures him that he's fine, but he expresses concern about his recent instability. Meanwhile, the police are on the verge of apprehending Lee Tae-man and Choi Jong-nam, but their window of opportunity is closing rapidly. Byung-man pays a visit to Chang-geun, expressing remorse for not giving more attention to the young individual who sought his help 27 years ago.