Hello, Monster/I Remember You (2015) : The Underrated Murder Mystery Series #422

I have a huge backlog of series and movies to talk about, but today, I felt most excited to sit down and share my thoughts on the 2015 series Hello, Monster (I Remember You).

The main reason I picked up this series? Park Bo-gum. After watching him in six dramas—When Life Gives You Tangerines (2025), Good Boy (2025), Record of Youth (2020), Encounter (2018), Love in the Moonlight (2016), Reply 1988 (2015)—and one film (Wonderland, 2024), I honestly needed to get over his innocent gaze and that sweet, disarming smile. I already knew his role here was on the darker side, maybe even a full-blown villain… so I had to find out for myself: would I still be this smitten after watching him as the bad guy?

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Plot of “Hello, Monster“/”I Remember You”

The story starts with Cha Ji-an (played by Jang Na-ra), a dedicated detective who arrives at a crime scene with her teammates from a special criminal investigation unit under the Korean Police. Lee Hyun (played by Seo In-guk) also shows up at the scene, while investigating a separate murder case. Lee Hyun is a genius criminal psychologist who works as a professor in the U.S. and returns to Korea after receiving a mysterious email related to the case. He’s sharp, fast, and incredibly thorough with his observations—but he also comes off as arrogant and the least friendly person in the room.

We soon get a glimpse of Lee Hyun’s childhood. He grew up in a motherless household. His father, Lee Jung-min, a psychologist working with the police, often dealt with dangerous criminals. Even as a 10-year-old, Hyun was unusually mature—a genius even. He practically raised his younger brother Min, who was always by his side.

At one point, Lee Jung-min was interviewing a young psychopathic criminal, Lee Joon-young… when the criminal slyly planted a seed of doubt in the father’s heart about his own son. After all, Hyun wasn’t like other kids—he cared for his workaholic father and baby brother like a grown-up, his analytical skills were beyond impressive… and yet, he was often found in odd, unsettling situations.

One day, while looking for his father, little Hyun wandered into the police station and had a brief but eerie encounter with the killer, Lee Joon-young. Their conversation was cut short when the father arrived. But before leaving, Joon-young promised Hyun they’d meet again. Not long after that, a distressed Lee Jung-min locked his son in the basement of their house. He still fed him, helped him with studies—but the damage was done. Hyun was heartbroken to learn that his father feared he might be a ‘monster’.

Then, one night, Joon-young escaped from jail and showed up at their house. He murdered Hyun’s father and disappeared. Little Min vanished too… leaving Hyun all alone.

Now, as an adult, Lee Hyun has fragmented memories of his childhood. The unsolved puzzle of his past somehow seems connected to the trail of murders happening in the present. Because of his profiling brilliance, Cha Ji-an’s team offers him a temporary position as an advisor.

But every crime Hyun solves comes with shadows of his own past… Is his father’s killer, Lee Joon-young, still alive?

Hyun still calls out for his little brother Min in his sleep…

Meanwhile, we learn that Cha Ji-an grew up in the same neighborhood as Lee Hyun. Her father was the prison guard accused of helping Joon-young escape—and he also disappeared the same night. Cha Ji-an grew up as the daughter of a ‘criminal’, ostracized and alone.

As a child, Ji-an had wanted to befriend Hyun… who was lonely too. But Hyun never took her hand. So she followed him from a distance, quietly watching over him. Now, as an adult, Cha Ji-an is still just as invested in him—if not more. It’s as if Lee Hyun is her only clue to finding Lee Joon-young. But will he be an ally in her search—or a threat?

As the two work together solving case after case, Hyun and Cha Ji-an grow closer. Hyun also finds a new friend in Lee Jun-ho, a forensic doctor and his neighbor. The team frequently crosses paths with a young attorney named Jung Sun-ho (played by Park Bo-gum), who keeps popping up as legal counsel for various criminal suspects—making him rather unpopular with Ji-an and the others.

As Hyun digs deeper into the murders, he starts suspecting the killer might actually be his long-lost younger brother, Min… now living under a new identity as the very attorney they keep running into.

It turns out that the motive behind the murders stemmed from Min’s unresolved anger and abandonment issues. He had been made to believe that Hyun had willingly left him behind. So Min started targeting people who had abandoned others in their lives—symbolically killing his brother over and over again.

Yet, despite all the bitterness, Min had secretly been leaving clues for Hyun, hoping to be found. Hyun’s foster parent had lied to him—saying Min had died. And Hyun, hurt and confused, had ignored the clues for years.

Eventually, Hyun confronts his brother. Not long after, Min becomes the target of a revenge attack aimed at Hyun. But this tragedy unexpectedly leads to the brothers reuniting. Though deeply conflicted about Min’s crimes, Hyun takes him in and starts caring for him—just like he used to back in the day.

Hyun slowly starts connecting the dots between the mysterious postcards sent by Min and an old trauma buried deep in his subconscious. A certain incident triggers his memory to resurface: their mother’s death. She had been killed by a criminal as revenge against their father. In an act of self-defense, little Hyun had shot the man. When their father arrived at the scene, he covered up the death and somehow wiped Hyun’s memory. But Min remembered everything—witnessing not one but two gruesome deaths.

Adult Hyun now blames himself for Min’s broken psyche… and the lives lost because of it.

Meanwhile, Joon-young, who’s been dropping cryptic messages for a while, finally reveals his identity and backstory. He was the result of a sexual assault and grew up hated and isolated. His mother eventually committed suicide, and he, in turn, killed his entire family—except the maid who had shown him kindness. Over the years, Joon-young murdered countless adults he deemed abusive, believing he was “saving” the children involved. Shockingly, Joon-young turns out to be none other than the friendly forensic doctor Jun-ho, who had been close to Hyun all along.

Hyun hopes that, through love and understanding, he can pull Min back from the darkness. He makes him promise to stop killing—and tells him, if he ever must kill again, to take his life instead.

Cha Ji-an, while sympathetic towards the brothers’ bond, struggles with the reality of Min’s crimes. The law may not have strong evidence against him, but she can’t turn a blind eye.

Joon-young, for his part, still shows an odd affection towards the two brothers—especially Min, whom he had raised after the death of their father. Min doesn’t fully understand the immorality of his actions, but seeing Hyun’s emotional turmoil helps him grasp the weight of his deeds.

In the end, Min tries to end the cycle. He sets out to make one final kill—but instead of Hyun, he tries to kill Joon-young. During the fight, Joon-young retaliates, stabbing Min and fleeing with his body.

A few days later, Joon-young resurfaces to say goodbye to Hyun. Hyun begs him to return Min’s body. It’s revealed that Min survived the stabbing—possibly even saved by Joon-young himself.

Hyun continues to stay in contact with his brother, giving him a choice: keep running from justice, or come back and face the consequences, which would allow him to live freely—as himself—and stay close to his brother.

In the final scene, we see Hyun and Cha Ji-an together, enjoying a quiet day as a couple. Hyun seems calm and grounded, but determined to chase Joon-young again in the near future. Min walks out of the hospital with a soft, satisfied smile—finally having the affection of his brother he had longed for over two decades. And in the crowd, Joon-young quietly watches Hyun, wearing a strangely pleasant look on his face…

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So, what was the conversation between little Lee Hyun and young Joon-young that changed the track of so many lives?

Joon-young spoke to Hyun about the critical period of life—the early years when a person’s conscience is formed, shaping what kind of human they’ll grow up to be.

He asked little Hyun, “What do you think of me?”
Hyun replied, “You’re different from others…”—without assigning it any positive or negative weight.
Joon-young told him, “You’re quite similar to me.”

That’s when Hyun, with a touch of sadness, confessed, “You know… my father thinks I’m a monster.”
Something he had read in his father’s journal.
Then he added, “But it’s not me. It’s my little brother, Min.”

Joon-young, who had endured brutal emotional neglect from his own family, perceived that Hyun too was being abused—misunderstood by the very person who was supposed to protect him.
And for the first time in his life, Joon-young felt seen—not as a killer or a criminal, but simply as a human.
Hyun didn’t judge him. He didn’t flinch. He listened.

In Joon-young’s twisted worldview, he believed he was doing Hyun a favor by killing his father—just like how he had “saved” many other children from the adults who hurt them.

As he fled the murder scene, he discovered that little Min had hidden in his car.
Joon-young took it as a sign of destiny—and raised Min as his own.
To him, Min wasn’t made into a monster—he was born one. Joon-young believed that by removing Min from Hyun’s life, he was also saving Hyun from turning into someone like himself.

During their conversation, little Hyun had asked, “What kind of adult do you think I’ll become?”
Joon-young, smiling faintly, answered, “You might become like me. Or maybe the complete opposite. There are many possibilities… and I’d love to see how that turns out.”

And that’s how it all began.

The unintentional killing Hyun committed as a child—done purely in self-defense—was the moment that shifted his father’s perception of him. From that point on, Lee Jung-min began to mistake Hyun’s maturity and emotional detachment for signs of a budding psychopath, never realizing that the true source of concern was Min.

It’s tragic, really.
The wrong son was feared.
The right signs were missed.
And that one brief conversation between a curious boy and a broken killer… ended up changing the course of three entire lives.

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My Fangirl Commentary

1. I absolutely loved the female lead played by Jang Na-ra. Her character felt so distinct from the typical K-drama heroines I’ve been watching lately. Cha Ji-an is fearless and kind—a petite detective taking down criminals like a total badass. I adored her playful banter with Hyun, who seems cold and arrogant on the surface. Ji-an isn’t your usual “girly girl” wearing florals and high heels… Nope, she struts around in cutesy shirts and skinny ripped jeans, flirts with Hyun like there’s no tomorrow, then instantly retracts with some unhinged comment whenever he doesn’t respond. It’s hilarious and charming all at once.
   
2. Seo In-guk is undoubtedly very handsome, and I’d love to see more of his work. His portrayal of Lee Hyun had the perfect mix of mystery, pain, and brilliance—his expressions alone carried so much depth.
   
3. Okay… can we please talk about our Bogummy now?!
   Park Bo-gum absolutely nailed the role of the psychopath, Lee Min. He’s so handsome, yet the eerie smile of attorney Jung Sun-ho (Min’s other identity) sends literal chills down your spine. I was getting a little frustrated in the early episodes when he didn’t show up (I had only seen him in lead roles before, so I guess I was still adjusting!)—but when he finally appeared, wow… there was something so magnetic about his presence. That icy gaze? Almost cruel. You never quite know what trick Sun-ho might have up his sleeve.
   
   But then… the character starts showing another side.
   The vulnerable, long-lost younger brother who spent his whole life feeling abandoned.
   
   With Hyun’s affection, Min’s humane side begins to surface. He’s still a murderer who doesn’t fully understand the weight of his actions—but there’s something softer in his expression, something curious, like a child trying to understand love for the first time.
   
   No wonder PBG’s acting was so praised for this role.
   
   What blows my mind even more? Reply 1988 (2015–2016) and Hello, Monster (2015) came out around the same time. I can’t believe Park Bo-gum played both the innocent, child-like Go game genius Choi Taek and the mysterious, emotionally twisted killer Lee Min… with such ease and nuance. He truly is an incredible actor.
   
4. After binge-watching so much romance-heavy content lately, I honestly enjoyed the lack of it in this series. Romance is sprinkled here and there, but it never becomes the main focus. Both leads are trying to navigate their personal traumas and professional responsibilities, while slowly developing trust and affection in a very natural, unforced way. That subtle growth felt refreshing.
   
5. Some people found the ending unsatisfactory… and I have to respectfully disagree.
   Sure, it could’ve been a little more dramatic or poetic—but honestly, how could a full-blown psychopath suddenly grow a conscience and turn himself in? (Talking about both Joon-young and Lee Min here.)
   
   These characters are evil geniuses who’ve mastered the art of wiping their tracks clean. That doesn’t mean they’ll never get caught… it just means the chase is going to be longer and messier. And honestly? That felt more realistic.
   
6. What the story does so well is leave you questioning:
   Were Min and Joon-young born monsters, or were they made that way by their circumstances?
   
   The show never gives a concrete answer. But in Hyun’s imagination, there’s this alternate version of Min—a normal, kind-hearted human being who never witnessed those murders, who was never dragged into Joon-young’s twisted world, who never felt abandoned by the one person he loved most.
   
   If only Hyun hadn’t told Joon-young about Min…
   If only they had grown up together…
   If only…Sigh. It’s haunting.

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All in all, Hello, Monster (I Remember You) was a gripping and emotionally layered series. It managed to hold a steady level of mystery right up till the end. The writing, the acting, the characters—all of it left a lasting impact on me.

I’d personally rate I Remember You / Hello, Monster 8.5/10.
I’m honestly bummed to see how underrated it is across different forums—those poor ratings had kept me from watching it earlier, and I wish I had discovered it sooner.

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