Memoir of a Murderer

Memoir of a Murderer is a 2017 South Korean crime thriller about a retired serial killer whose memory is dissolving from Alzheimer's disease. Kim Byeong-soo (Sul Kyung-gu) buried his crimes decades ago, but when a string of new murders hits his town, he becomes convinced that his daughter's new boyfriend, police officer Tae-joo (Kim Nam-gil), is the one responsible.

Directed by Won Shin-yun from a screenplay he co-wrote with Hwang Jo-yoon, the film adapts Kim Young-ha's novel, published in English as Diary of a Murderer. Sul Kyung-gu leads the cast as a former veterinarian who records his own days on tape and in a written memoir because he can no longer trust what he remembers, while Kim Nam-gil plays the policeman whose case against him nobody else will believe. Kim Seol-hyun plays Byeong-soo's daughter Eun-hee, and Oh Dal-su plays Byeong-man, the one officer still willing to hear Byeong-soo out. Hwang Seok-jeong appears as a classmate from Byeong-soo's poetry class whose attention he finds hard to shake, and Gil Hae-yeon plays his older sister Maria, a nun he keeps turning to when his own memory fails him.

The small town setting closes in as Byeong-soo's own notes start to contradict what he thought he saw, and the police treat his warnings as the confusion of a sick old man rather than a lead worth checking. His daughter's growing closeness to Tae-joo turns every family dinner into something Byeong-soo has to watch through his own unreliable memory, unsure from one day to the next what he has already told either of them.

Memoir of a Murderer opened in South Korean theatres on 6 September 2017 and led the national box office for eleven straight days, passing two million admissions within two weeks, the first Korean thriller of that year to reach the mark. It later screened in the Thrill strand of the 61st BFI London Film Festival that October, part of a release that also reached Australia, New Zealand, France, Turkey, Taiwan, Japan and the Philippines.

A director's cut released later runs 128 minutes against the theatrical version's 118, adding ten minutes of footage and a different final act. Sul Kyung-gu's performance went on to win Best Actor at the 17th Director's Cut Awards in 2017 and again at the 9th Korea Film Reporters Association Film Awards the following year, honors that came alongside nominations for Sul and for Kim Seol-hyun at the 1st Seoul Awards.

Memoir of a Murderer keeps finding new viewers because its central device, a killer whose Alzheimer's disease makes his own memory the least trustworthy witness in the story, turns a familiar cat-and-mouse plot into something closer to a puzzle. The film travelled well beyond Korea for a psychological thriller of its kind, screening in the Thrill strand of the 61st BFI London Film Festival in October 2017, and it has stayed in circulation since on streaming platforms including Netflix. Sul Kyung-gu's performance, which won Best Actor honors from two separate Korean film bodies within a year of the release, remains the reason many viewers watch it a second time to catch what his character does and does not actually remember.