Psychopath Diary: The K-Drama Where a Timid Man Thinks He’s a Serial Killer
What if you found a serial killer’s diary and, after losing your memory, became convinced it was yours?
That is the setup for Psychopath Diary, the 2019 thriller starring Yoon Shi-yoon, Jung In-sun, and Park Sung-hoon. Yoon Shi-yoon plays Yook Dong-sik, a timid employee at a securities company who ends up with the diary after stumbling onto a murder. An accident leaves him with amnesia, and the diary becomes the only real clue he has about who he might have been.
Unfortunately for Dong-sik, the diary describes a serial killer.
So he reaches the wrong conclusion.
Watch Pyscopath Diary for free on Amasian TV
The diary becomes Dong-sik’s new identity
Before the accident, Dong-sik is used to being pushed around. He takes the blame for mistakes at work and struggles to stand up for himself. Then, almost immediately, his life becomes much stranger.
He witnesses a murder, escapes with the killer’s diary, gets hit by a police car, and wakes up without his memories.
The diary contains detailed records of murders, so Dong-sik has no reason to think it belongs to somebody else. As far as he knows, this is evidence of a life he can’t remember.
That misunderstanding drives the entire premise.
Dong-sik mistakes himself for a psychopath serial killer after losing his memory and finding the diary. The real owner of the diary is Seo In-woo, played by Park Sung-hoon.
The interesting part is what happens to Dong-sik afterward
The comedy comes from watching a man who has spent his life being intimidated by other people suddenly believe that he is capable of murder.
Dong-sik starts interpreting his own behavior differently. Small acts of confidence can take on a completely different meaning once he believes he is a dangerous criminal.
That gives Yoon Shi-yoon an unusual performance challenge. He isn’t simply playing a timid office worker throughout the drama. Dong-sik’s understanding of himself keeps changing, even though the audience knows that his basic assumption about the diary is wrong.
Meanwhile, the actual killer has a very different problem.
The real serial killer needs his diary back
Seo In-woo isn’t trying to discover whether he is dangerous. He already knows exactly who he is.
He is the real serial killer, and losing the diary creates a problem because it contains a record of his crimes. Dong-sik, meanwhile, is walking around with the diary while believing its contents describe his own past.
That creates an unusual situation where the two men are operating with completely different versions of the truth.
Dong-sik is frightened of what he thinks he has done.
In-woo is worried about what Dong-sik has accidentally discovered.
The tension between those two perspectives is one of the drama’s strongest recurring ideas.
A crime drama with a very strange sense of humor
Psychopath Diary aired for 16 episodes from November 2019 through January 2020. Its central story gives it plenty of conventional crime-thriller material, but the mistaken identity premise lets the drama repeatedly undercut that tension with comedy.
That’s also why the premise remains easy to remember years later.
A man finds a murder diary.
He loses his memory.
He assumes he’s the murderer.
And the actual murderer is trying to get the diary back.
There aren’t many K-dramas that start from quite that combination of circumstances.