Bodil, an accomplished judge, embarks on a weekend escapade to Ostend, Belgium, accompanied by her close friend Isabel. Both women intend to act as each other's alibis while secretly engaging in affairs, blissfully unaware of the chaos that awaits them. Upon their arrival, Isabel heads out to a vibrant club, while Bodil chooses to attend a captivating lecture led by Michael Samuels. In a twist of fate, Bodil has Isabel's phone with her and is responsible for maintaining the façade of normalcy by communicating with Isabel's husband, Luuk, through a series of texts.
As the weekend unfolds, Bodil makes a bold move by inviting Michael to her home for an overnight stay. However, the tides turn when Luuk calls Bodil in distress, revealing he has fallen from the stairs and broken his ankle. Bodil, caught in the shower, takes this urgent news to heart and contacts Isabel on a burner phone to warn her about the incident. She strategically places a house key under the mat and leaves Isabel's phone on the table, making it easy for her to retrieve it on her way back to the Netherlands.
While relaxing on the beach with Michael, Bodil makes it clear that their connection isn’t serious. She coldly states that if she encountered him on the street, she would act as though they were strangers. Hurt by her words, Michael leaves, prompting Bodil to find solace in the ocean waves. Upon her return home, however, horror strikes as she stumbles upon a gruesome scene involving a pool of blood, shattered pottery, and the inexplicable absence of Isabel. The authorities are summoned, and they quickly ascertain that the blood matches Isabel's profile, leading them to question Bodil about her whereabouts during the time of the murder. Despite her claims of being with Michael, he later retracts his admission, intensifying the intrigue.
The situation escalates further when Isabel's phone reveals a shocking photo of her lying lifeless on the floor, her throat brutally cut. Alongside this devastating image is a cryptic text mentioning "Zadkin" and a message from an anonymous hitman declaring the job finished. The police suspect a string-like weapon, possibly a piano wire, was used in the deadly act. Amidst this chaos, Bodil receives a mysterious book titled "Night Walker,” which she dismisses as inconsequential. Confiding in her husband, Milan Saber, about Isabel's affair deepens her predicament when Luuk, unwilling to believe her, confronts her about the possibility of tracking Isabel.
As various twists unveil, a lawyer representing Bodil takes her to the police station for questioning, where she is warned not to leave the country. In a moment of desperation, Bodil seeks out Michael again, confronting him about his silence regarding their history. He expresses concern and suggests he could retract his statement to the police. A pivotal moment arrives when the police acquire footage from the hotel showcasing Isabel kissing Bodil's sister, Yara Backer, leading to her arrest.
During a heart-to-heart with Milan, Bodil confesses that she desired Isabel to end her relationship with Luuk, as he smothered her. Through a series of astounding events, Yara, who remains on bail, gifts Bodil a taser for protection, suggesting that she might have been the actual target instead of Isabel. A critical development occurs when Bodil's son reveals a password to his father’s laptop, leading her to a shocking discovery—a live feed of herself in her own living room, indicating a deliberate invasion of privacy.
Bodil's quest for answers leads her to Milan's laptop, where a folder supposedly containing incriminating video logs appears mysteriously devoid of content when accessed. In a moment of frantic decision-making, she takes a taxi to Michael's residence, where she finds an ominous missing note on a piano and grows increasingly suspicious of him. Caught off guard, she finds Milan waiting outside, leading her back home after a chaotic encounter.
As Bodil grapples with increasing paranoia, she discovers that Luuk appeared to have attempted suicide. Milan, claiming to be a doctor, manages to save him, yet suspicion looms in Bodil's mind regarding her husband's true motives. After an intense confrontation, involving Bodil tasing Milan and tying him up, the truth begins to emerge. Luuk confesses to having hired a hitman for Bodil's demise, revealing a tragic mix-up that saw Isabel murdered instead. In a gripping climax, an armed confrontation ensues, and Bodil is forced to defend herself, leading to Luuk's death.
As the dust settles, the police determine that Bodil acted in self-defense, clearing her of any wrongdoing. Just as she attempts to reconnect with her sister Yara, a stunning revelation comes to light. In a rush, Bodil learns that Isabel is alive and well, having veiled her demise with the help of Yara. Isabel explains her motive for faking her death was to escape the grip of Luuk, revealing that she increased the hitman's fee in order to save Bodil. With an overwhelming sense of relief and gratitude, Bodil reunites with Isabel, entrusting her sister with her passport as plans to escape the past take shape anew.