Memoir of a Murderer

After killing his abusive father as a teenager, Byeong-soo (Sol Kyung-gu) begins to believe there are people who deserve to die. During his killing spree, he buries his victims in a bamboo grove. After killing a woman, he gets into a car accident and injures his head, resulting in degenerative Alzheimer's disease. He stops killing, resumes his job as a veterinarian, and continues caring for his daughter Eun-hee (Kim Seol-hyun).

After multiple visits to a nearby police station (as he forgets where he lives), Byeong-soo strikes up a friendship with policeman Byeong-man (Oh Dal-su). At Eun-hee's behest, Byeong-soo uses a recorder to maintain his routines. He types everything he can remember into a memoir and saves it on his laptop. He also goes to a poetry class, where his poetic depictions of murders attracts classmate Jo Yeon-joo (Hwang Seok-jeong), much to his annoyance.

When the small town is shaken by the murders of two young women, Byeong-soo is confused and wonders if he did the killing. On the way back from the bamboo grove (to check for new burial sites), Byeong-soo hits another car. He notices a bloody bag in the popped-open trunk and collects blood on his handkerchief. The car's driver claims it is a deer's corpse and drives away without exchanging contact information.

After ascertaining the blood sample is human, Byeong-soo anonymously calls the police, describing the encounter and the car's make and license plate. The tip is considered a prank as the car's driver is policeman Min Tae-joo (Kim Nam-gil). Byeong-soo also asks Byeong-man to run the license plate separately. Instinctively realizing Tae-joo is a serial killer, Byeong-soo deduces where he was taking the body to. He finds the body and tips the police, catching Tae-joo's attention.

Tae-joo goes to Byeong-soo's clinic, where he meets Eun-hee. After a short while, the two begin dating. Byeong-soo sees the pair but does not recognize Tae-joo. After Byeong-man tells him about the license plate's owner, Byeong-soo realizes Tae-joo is the killer who uses his daughter to taunt and threaten him. He gives Byeong-man the handkerchief with the blood, telling him it's from Tae-joo's car.

Suppressing his self-doubts, Byeong-soo is determined to kill Tae-joo, but his failing mind and body betray him. He starts experiencing hallucinations and a week's worth of memory is erased.

Byeong-soo wakes up to find himself tied up in his bedroom, with Tae-joo reading and liberally editing his memoir. Tae-joo admits to being the killer and having swapped the handkerchief with the blood sample. Byeong-soo tries to grab his bag for a weapon but fails and spills its contents onto the floor. Tae-joo threatens to kill Eun-hee unless Byeong-soo takes the blame for his crimes, then tranquilizes him. Byeong-soo wakes up and only vaguely remembers what happened.

Fearing for his daughter's safety, Byeong-soo orders her to stay with his sister Maria (Gil Hae-yeon) at her convent. He follows Tae-joo to an abandoned house and finds footage of Yeon-joo being held hostage. When he presents this evidence to the police, they suspect Byeong-soo himself is responsible. Upon trying to call Maria to prove Eun-hee's safety, Byeong-soo recalls Maria committed suicide shortly after their father's death. Police begin digging up the bamboo grove, finding the remains of past victims and Yeon-joo.

At home, Byeong-soo recalls who his final victim was - his adulterous wife. Before dying, she said Eun-hee was not his biological daughter. Arriving home after the car crash, Byeong-soo's injury causes him to forget this revelation and he continues caring for her. Byeong-soo remembers almost strangling Eun-hee, mistaking her for his wife, and becomes convinced that he might have killed his daughter in a fit of insanity.

Guilt-ridden, Byeong-soo prepares to kill himself. However, he then hears Tae-joo confessing his crimes as during their earlier confrontation, he accidentally turned on his recorder.

Renewed with vigor, Byeong-soo calls Byeong-man and convinces him Tae-joo is the killer. Byeong-man follows Tae-joo to a cabin, where Tae-joo strangles him. He ties up Eun-hee after she sees the body. Byeong-soo arrives at the cabin. After a fight during which his condition almost cost him his life, with Eun-hee's help, Byeong-soo overpowers and kills Tae-joo. Eun-hee, having learned from Tae-joo earlier that her mother's body was found in the bamboo grove, is terrified of her father. He assures Eun-hee that she is not a murderer's daughter, as they are not blood-related. Byeong-soo is subsequently incarcerated and processed into an internment facility.

Eun-hee listens to Byeong-soo's last recording and decides to forgive him. She visits Byeong-soo, whose memory has deteriorated to the point that he mistakes her for Maria. In a brief moment of clarity, Byeong-soo decides to kill himself before wanting to live more and remember what he is -- a murderer. Before his suicide, his symptoms manifest again.

Byeong-soo stands outside a train tunnel. He holds up his daughter's locket with the photo of Tae-joo inside. He sees Tae-joo smirking at him and thinks to himself, "Don't trust your memory. Min Tae-joo is still alive".

• Sol Kyung-gu as Kim Byeong-soo, a retired serial killer with Alzheimer's disease. He only kills those who have committed sins "equally worse," and he makes them pay the price.[8]
  • Shin Ki-joon as Kim Byeong-soo (young)
• Kim Nam-gil as Tae-joo, a local policeman whom Kim suspects to be a serial killer.[9]
• Kim Seol-hyun as Kim Eun-hee, Byeong-soo's daughter who takes care of him because of his disease. She becomes Tae-joo's girlfriend.[10]
• Oh Dal-su as Byeong-man, a policeman determined on finding murderers of the town.
• Hwang Seok-jeong as Jo Yeon-joo, a woman taking poetry class with Byeong-soo's, whom she annoys, flirts with, and doesn't take seriously.
• Gil Hae-yeon as Maria, a nun and Byeong-soo's older sister.
  • Kim Hye-yoon as young Maria
• Kim Han-joon as detective
• Kim Dong-hee
• Kim Jung-young
• Jo Jae-yoon as doctor

Memoir of a Murderer was released in South Korea on 6 September 2017. According to its distributor Showbox, the film was scheduled to open in North America on 8 September 2017, two days after its domestic release. It was also released in Australia, New Zealand, France, Turkey, Taiwan, Japan and the Philippines.[11]

Memoir of a Murderer was also shown in the Thrill section at the 61st edition of the BFI London Film Festival, which runs from 4–15 October.[12]

The film reached over 1 million admissions in just 5 days of its release (6–10 September) topping the Korean box office and grossing US$8.6 million.[1] As of 17 September, the film marked 2.06 million admissions grossing US$14.7 million nationwide, the first South Korean thriller film to reach 2 million ticket sales in 2017.[14][15]

• Memoir of a Murderer at IMDb 
• Memoir of a Murderer at HanCinema
• Memoir of a Murderer at the Korean Movie Database