[K Drama] Queen Mantis Plot Summary & Ending Spoiler

Korean Drama “Queen Mantis” is a crime thriller drama airing on SBS from September 5, 2025. The series follows the aftermath of the capture of a notorious female serial killer, known as “Queen Mantis,” when, twenty years later, a new string of copycat murders begins.

The drama centers on Jung I-shin, the infamous killer dubbed “Queen Mantis,” who, after being imprisoned, inspires a copycat to commit a series of murders. Her estranged son, Detective Cha Soo-yeol—who has harbored lifelong resentment towards his mother—finds himself forced into a reluctant partnership with her to solve the case, leading to a high-stakes psychological crime drama.

Queen Mantis: The Murderer’s Outing is based on the 2017 French drama “La Mante.” In the original, female serial killer Jeanne Deber (the “Mantis”) is approached by police 25 years after her crimes to help catch a copycat, on the condition that her estranged son Damien, a detective, works the case by her side. The story delves into Jeanne’s traumatic upbringing and the circumstances that made her a murderer, while the copycat is revealed to be a child of one of her victims, continuing a cycle of darkness and revenge.

The series received high praise for its intense mother-son dynamic, gripping mysteries, and suspenseful crime psychology, with critically acclaimed performances from Karole Bouquet as Jeanne and Fred Testot as Damien in the original. “Queen Mantis: The Murderer’s Outing” skillfully portrays a unique female serial killer character, the darkness of Paris, and the realistic investigation process.

K Drama Queen Mantis

Korean: 사마귀 : 살인자의 외출 | Japanese: カマキリ: 殺人者の外出 | Chinese: 螳螂
Genre: Crime, Thriller, Mystery
Broadcast Period: September 5, 2025–September 27, 2025 (scheduled)
Airtime: Fridays and Saturdays at 9:50 PM KST
Director: Byun Young-joo
Screenwriter: Lee Young-jong (Spring in Seoul, The Roundup 2, Hunt adaptation)
Original Work: French drama La Mante (TF1/Netflix)
Cast: Go Hyun-jung, Jang Dong-yoon, Jo Sung-ha, Lee El, Kim Bo-ra, and more
Production Format: Pre-produced (filming: October 2024–February 2025)
Episodes: 8
Metwork: Netflix, Wavve

K Drama Queen Mantis Cast

Go Hyun-jung as Jung I-shin
The female serial killer known as the “Mantis.” Imprisoned for her brutal murders 20 years ago.
Jang Dong-yoon as Cha Soo-yeol
A detective and Jung I-shin’s estranged son who reluctantly partners with her in investigating copycat killings.
Jo Sung-ha as Jong-ho
A police officer who advises Cha Soo-yeol to become a detective.
Lee El as Na-hee
A female police officer involved in the investigation.
Kim Bo-ra as Lee Jung-yeon
The president of a pottery company and Cha Soo-yeol’s wife.
Han Si-a as Eun-ae
A supporting character.

K Drama Queen Mantis plot Summary

In the 1990s, there was a female serial killer who terrorized France. She was nicknamed “La Mante” (The Mantis). Like the insect mantis that bites off the heads of males after mating, she brutally selected and murdered men she considered “trash” from society, dismembering their bodies and heads. Her name was Jung Eui-shin (original: Jeanne Deber).

The police succeeded in arresting her by DNA and fingerprints collected at the fifth murder scene. However, the only clear evidence they had was from the last incident. Jung Eui-shin confessed to all her crimes on a single condition: that her young son Cha Soo-yeol (original: Damien Carrot) be protected. She wanted her son to live a new life free from the stigma of being the “son of a murderer.” In court, she claimed her killings were “the realization of justice,” showing no remorse.

Twenty-three years later, a horrific string of copycat murders mimicking Jung Eui-shin’s methods occur. The perpetrator kills victims in exactly the same way as the Mantis did, then arranges their bodies neatly in places where anyone can find them, as if displaying an art piece, intentionally attracting police and media attention to spread fear.

Upon hearing this news from prison, Jung Eui-shin sends a message expressing her willingness to cooperate with investigators. Her only condition is that her son, now a police officer, Cha Soo-yeol, must lead the investigation personally. This demand causes great pain for Soo-yeol. He had spent his life trying to erase his mother’s existence, changing his name, hiding his past, and not even telling his wife Lee Jung-hyun about his family history. This moment tears open those wounds again. But with copycat killings continuing and no other leads, Soo-yeol has no choice but to accept cooperation with his mother.

During the secret “Mantis Project,” Soo-yeol’s emotions are shaken when he meets his mother after 23 years, but Jung Eui-shin welcomes him coldly and expressionlessly. The true reason for her request is less about the investigation and more about her desperate curiosity and longing for her son who is the only normal and proud person she raised despite her twisted life.

While the investigation with his mother proceeds, Soo-yeol’s wife Lee Jung-hyun sees the extreme distress her husband suffers from taking on the case and begins her own investigation to uncover his secret. Meanwhile, Soo-yeol’s childhood friend Park Min-jae and cult follower Seo Gu-han come under suspicion, but the copycat killings continue, raising doubts that Jung Eui-shin might be controlling the crimes from prison.

As Soo-yeol delves deeper into the mystery, he discovers a sixth murder his mother never confessed to: the killing of his own biological father. Jung Eui-shin admits she had no choice but to kill her violent husband to save her son. This was her first experience deeply imprinted with a sense of “justice punishing evil men.” The victims she chose appeared ordinary or successful but were actually abusers of women, and she believed she was a “moral judge” delivering punishment.

Jung Eui-shin was not a psychopath or a madwoman. She was not totally lacking empathy and felt profound remorse and guilt over the damage her crimes caused her son. All of her crimes were carried out under a meticulous plan, not impulse. She was a twisted moral killer aware of being a monster.

Through the cooperative investigation, Soo-yeol gradually comes to understand his mother is not a mere mad killer but a complex figure armed with extreme trauma and a specific sense of purpose. Although he cannot forgive her crimes, his blind hatred begins to falter.

Meanwhile, Soo-yeol’s grandfather Jeong Hyun-nam, who took care of him, always told Soo-yeol that Jung Eui-shin was a demon, encouraging him to hate her. However, Soo-yeol accidentally sees videos of young Jung Eui-shin’s facade therapy and uncovers a shocking truth: Jung’s mother was not killed by lions in Africa as he was told, but was actually murdered by Jeong Hyun-nam himself upon discovering his wife’s efforts to stop abusive behavior against his daughter.

Young Jung Eui-shin remembered her mother’s death as caused by lions because of a lion emblem on her father’s necklace. Even more shocking is that Soo-yeol’s biological father was Jeong Hyun-nam, whom he trusted and respected. Jung Eui-shin was raped by her father and pregnant, keeping that horrifying secret her entire life.

Knowing all this, Soo-yeol attempts to kill Jeong Hyun-nam, his biological father and grandfather. But Jung Eui-shin stops him, not wanting her son to walk the same path, and confronts Jeong Hyun-nam herself. Having his ugly secrets revealed and completely dominated by his daughter, Jeong Hyun-nam despaired and took his own life, completing Jung Eui-shin’s final revenge.

The copycat’s crimes grow increasingly brutal, and Jung Eui-shin suspects the culprit is someone involved in her crimes because the patterns perfectly replicate her past crime scenes. Upon hearing a lullaby at the fifth copycat murder scene, she finds a crucial clue. That lullaby was the song she sang during her past murders, and only the victim’s family could have heard it. Investigators track down the family of Jung’s fifth victim and discover they had a transgender son who struggled with gender identity.

At that moment, the copycat calls Jung Eui-shin directly, leaving a cryptic message, “I made your son Soo-yeol happy.” This hint makes Soo-yeol think of his wife Lee Jung-hyun, who brought him love and happiness, and their mutual friend Seo Ara — who turns out to be the transgender son.

Seo Ara suffered horrific abuse from her father due to her gender identity and had worshiped Jung Eui-shin as a savior. However, due to gender reassignment surgery complications and societal prejudice, she lived labeled as a “monster,” growing ever more angered by the world and men who abandoned her. She sought to continue the Mantis’ mission, pursuing twisted justice.

K Drama Queen Mantis Ending

Seo Ara kidnaps Soo-yeol’s wife Lee Jung-hyun and proposes to exchange herself for Jung I-shin. At this moment, Jung I-shin declares without hesitation that she will go. “I want to return not as a monster, but as a mother.” For the first time in her life, she chooses to protect someone not by killing but by offering her own body.

At the hostage exchange site, Jung I-shin confronts Seo Ara. While Seo Ara worships Jung I-shin, she also harbors hatred towards her for creating her life’s misery and eventually abandoning her. Jung I-shin coldly reads Seo Ara’s psychology and engages her in conversation to absorb and neutralize her anger and obsession.

Eventually, Jung I-shin and Lee Jung-hyun cleverly escape, while a desperate Seo Ara, after a standoff with police, takes her own life.

After everything ends, Soo-yeol visits his mother one last time before she returns to prison. Jung I-shin quietly reveals all she had never spoken of before—her father’s abuse, the murder to protect her son from her husband, and the deep guilt over the suffering her son endured because of it. She says, “I do not regret what I did. But the pain you suffered is a burden I will carry for life.”

Soo-yeol confesses to her that he will soon become a father himself and, for the first time ever, calls her “mom” and embraces her. Jung I-shin, who had maintained her strength until that moment, finally breaks down and sheds tears in her prison cell after her son leaves. She finds her last solace and redemption not as the “serial killer Mantis” but as “mother Jung I-shin.”

The story ends with Cha Soo-yeol freeing himself from hatred and wounds, gaining courage to move forward with his new family.

Korean Drama Queen Mantis Spoiler

Seo Ara struggled with gender identity since childhood and was abused by her father because of it. However, when the father who tormented her was killed by Jung E-shin, she was freed from that pain. Although Seo Ara tried to appear as a woman, her efforts were crushed by prejudice, discrimination, and the despair she felt toward her own body. This led her into deep self-hatred, seeing herself as “neither a real woman nor a man, but a monster,” and eventually she followed Jung E-shin to become a murderer.