#1 Serial Killer (2013) Full Movie Summary & Plot Explained

Amber Sterling Kenzie Dalton is a young, striking blonde who finds her evening hinged on a failing phone connection as she exits an elevator and heads toward the parking garage. Her senses sharpen in the dim lot as she reaches her SUV, fumbling through her purse and key ring for the right car key. In a sudden moment of danger, a man dressed in black with a white mask grabs her by the hair and presses a knife to her throat, whispering in an Asian accent for her to get in the car. This terrifying encounter unfolds as a single, breathless sequence of fear and coercion, leaving Amber terrified and desperate to survive. The scene foreshadows a chilling pattern: a killer who will stop at nothing to control his victim and his own narrative.

Three days earlier, the narrative tightens around the office of HK & Chang Imports, where Eddy Tsai works alongside others including his quiet desk mate Micah Betancourt. Eddy’s presence is noted by Mr. Chang, a boss who values results and who senses something a little off about Eddy’s demeanor. The office hums with small moments of humor and tension as coworkers gossip and Eddy navigates a place where culture, ambition, and flirtation mingle. A new associate from Hong Kong, Karena Lee, arrives, and Eddy’s colleagues observe a cautious dynamic between him and her, while Karena herself tries to bridge cultural gaps with Eddy’s reticence and guardedness. The human texture of the workplace—humor, discomfort, yearning, and power dynamics—begins to color Eddy’s choices and justifications.

In the background, Eddy’s private world grows darker. He studies serial killers and movies about dangerous minds, collecting odd relics and manuals of danger, and films himself reflecting on Ted Bundy’s infamous maxim that killers blend into ordinary life. A macabre store visit yields gloves once worn by Ted Bundy, and Eddy begins to test the boundaries of his own moral line with a homemade mannequin bearing his father’s face. The imagery is stark and unsettling, foreshadowing a man who will soon blur lines between fantasy and action. His mother’s messages are erased, his ambitions bubble, and he cultivates a cold self-story: a man who believes he is capable of enacting control through fear and violence.

As Amber’s social world unfolds, Eddy’s restraint unravels in small, pointed ways. At lunch, he studies serial killers and is teased by colleagues, while Karena looks for connection and safety in his company. Eddy’s increasingly unsettling behaviors collide with his work life: Mr. Chang hints at relationships, asks Eddy to bring more attractive interns from his graduate program, and praises his early success as a path toward management. The tension deepens when Karena expresses homesickness and a longing for meaningful connection, prompting Eddy to open up in ways that feel intimate yet dangerously unbalanced.

Amber’s entry into the story’s foreground accelerates when Eddy confronts a mix of ambition, insecurity, and jealousy. In the office elevator, Karena notes Eddy’s fragile ego as he contemplates a future with a powerful boss and a complicated relationship with Karena. The murder of Amber becomes the brutal fulcrum of the plot, as Eddy’s fear and desperation explode into violence in the parking garage—he abandons his mask, reveals his weapon, and commits a brutal stabbing that leaves Amber gravely wounded and then unconscious. The aftermath is a torrent of guilt, bravado, and the unsettling chant of self-affirmation that Eddy repeats: “I am the most cold-hearted son of a bitch you’ll ever meet.”

Back at work, the investigation begins. A police officer questions Eddy about his whereabouts during the crucial time, and Eddy’s discomfort hints at something deeper than nerves. Meanwhile Karena and Eddy’s fragile bond develops into something more dangerous as Eddy’s obsession with Karena intensifies. Eddy’s private rehearsals of murder escalate into a disturbing sequence of planning and manipulation: he and Karena fantasize about killing Mr. Chang, with Eddy urging Karena to imagine herself as a killer in a symbiotic partnership. The relationship becomes a study in coercive romance, control, and deadly fantasy.

The story threads converge as Eddy’s professional ascent—garnered through manipulation and shrewd political moves—collides with his escalating personal violence. Mr. Chang’s suspicions fuse with Eddy’s mounting bravado, culminating in a brutal confrontation that leaves Eddy free but emotionally hollow, and Karena increasingly caught between fear, fascination, and a need to survive. The couple’s shared fantasy collapses under the weight of real-world consequences, and Eddy’s world begins to revolve around a chilling plan to keep Karena close and to redefine their lives through crime.

Eddy’s next moves, both intimate and violent, push the boundaries of loyalty and fear. He stages a dramatic act against Mr. Chang, seizing control of the situation and forcibly removing his former mentor from power. The act marks a turning point: Eddy has aligned himself with the idea that danger is a shared language for him and Karena, and that their bond can be strengthened through fear, secrecy, and shared complicity. The pair’s conversation spirals into a night of reckless decisions, including a disturbing display of power and a continuing fantasy that murder can forge an unbreakable partnership.

In a final, chilling turn, Eddy’s calculus about fear, control, and relationship momentum culminates in a deliberate plan to turn Karena into a partner in crime. The two rehearse and enact a sequence of violent acts, including a staged setup that blurs the line between protector and predator. Their collaboration reaches a breaking point as the truth of Eddy’s capacity for violence is laid bare, and Karena is drawn into the darkest aspects of her own psyche. The result is a horrifying bid for dominion over life and death, with Eddy asserting his own ruthless creed and Karena’s loyalties tested to the limit.

The investigation intensifies as the police collect evidence—including a string of videos and a wall of images detailing Eddy’s fixation on killers and victims. Tricia Arnold [Shoshana Bush] and others in the office weigh Eddy’s persona against the mounting body of evidence, while investigators wonder how a quiet, diligent coworker could harbor such a dangerous secret. The detectives piece together the timeline: Eddy’s outward polish cloaks a violent core, and his self-created narrative about being “the most cold-hearted” man becomes tragically literal.

In a final, brutal coda, Eddy’s violence does not end with the high-profile confrontation. One month later, a routine car start fails for [Tricia Arnold], and the killer emerges from the backseat to strike once more, strangling her as Karena records the scene. The camera becomes the weapon and witness, sealing a new chapter of fear and control that lingers beyond the cinema’s frame. The last shot leaves audiences with a haunting reminder: violence can be intimate, and power can reside behind a polite smile.