Memoir of a Murderer

Memoir of a Murderer (살인자의 기억법) is a 2017 South Korean mystery thriller directed by Won Shin-yun. It is adapted from the bestselling novel by Kim Young-ha. Sul Kyung-gu plays Kim Byung-su, an aging veterinarian in a quiet rural town. He is hiding a terrible past: for years he killed people as a self-appointed vigilante, and he stopped only after an accident seventeen years ago.

Now Byung-su has vascular dementia and Alzheimer's disease, and his memories are slipping away. He records his thoughts on a voice recorder and in notes. He lives with his beloved daughter Eun-hee (Kim Seol-hyun). A car accident brings him into contact with a police officer, Min Tae-ju (Kim Nam-gil), and Byung-su becomes sure the man is a killer like himself. He believes Tae-ju recognized him too.

When Tae-ju starts getting close to Eun-hee, Byung-su tries desperately to protect her. The problem is that he cannot trust his own mind. The film becomes a tense cat-and-mouse game in which neither Byung-su nor the audience can be sure what is real and what his illness is inventing.

The film asks what is left of a person when their memory is gone. Byung-su is losing the story he tells about himself, but, as he says, his hands still remember how to kill. Won Shin-yun uses an unreliable narrator to make viewers share Byung-su's doubt, so every scene can be read in more than one way.

Underneath the thriller is a story about guilt and love. A man who has done monstrous things still loves his daughter and wants to protect her. The film suggests that identity is not just a set of memories. It is also habits, instincts and bonds that remain, for better or worse, after memory fades.

Tae-ju really is a killer: Read literally, Byung-su correctly spots a fellow predator, and his memory, however broken, protects his daughter.

The film came out in 2017 as part of a strong run of Korean serial-killer thrillers. It stood out because it put a killer with dementia at the center and told the story through an unreliable narrator. It adapted one of Kim Young-ha's best-known novels and was a commercial success, earning about US$19.5 million. A director's cut was later released.

Critics such as The Reel Bits called it a top-notch thriller that keeps audiences thinking after the credits. They praised how it uses the unreliable narrator and Sul Kyung-gu's physical, emaciated performance, which the Korea Herald highlighted. The same novel was later adapted again as the Japanese film Memoirs of a Murderer, which shows how appealing the source material has been across cultures.

The film scores about 7.2 on IMDb. Viewers and critics widely praised Sul Kyung-gu's performance, the gripping premise, and the clever use of an unreliable narrator that keeps viewers guessing.

The most common criticism is about the finale. Some reviewers felt it slides into melodrama, with over-the-top twists and a long, drawn-out fight scene. Others were frustrated or fascinated by the ambiguity about what is real. Overall, it is seen as a strong, thought-provoking Korean thriller whose ending splits opinion.