The narrative unfolds as Isabel and her brother-in-law exit a nightclub, where they unexpectedly encounter a figure from her brother-in-law’s past during his incarceration. This chance meeting is captured in photographs, and soon after, Isabel makes her way to the train station, anticipating her ride home.
At the train station, Isabel begins to experience visions of mystical creatures, setting an eerie tone for the story. Meanwhile, a detective grapples with the murder of his partner. As he delves deeper into the investigation, he uncovers the dark dealings of his former partner, only to be cautioned by his chief to cease his inquiries to protect the pension benefits owed to the deceased cop's widow.
Portraying a devout Catholic, Isabel works at a nursery school and becomes increasingly concerned about one of her disturbed students. Disturbingly, she discovers that the child is being abused by her father. During the investigation into the dirty cop, a street thug is questioned, and after a conversation with Isabel's brother-in-law, struggles ensue, leading to the thug's demise.
In a poignant scene, the detective visits the widow of his late partner to deliver grim news regarding the potential risks to her pension if investigations proceed. She reacts violently, sending them away. Later, during the detective’s birthday celebration—marked by an innocent muffin—she seduces him, taking advantage of their shared grief from their lost spouses, asserting that no crime has taken place. She reveals her husband's unsavory past, including an incident of abuse involving an inmate, who is, notably, Isabel's brother-in-law.
As Isabel continues to witness these mystical beings, tragedy strikes when her husband's dog dies, followed by her husband's passing, leaving her deeply mournful. Flashbacks reveal a complicated affair with her brother-in-law, and soon after, Isabel learns of her surprising pregnancy, which she perceives as a miracle. When she shares this news during dinner, tensions flare, prompting her husband’s family to ask her to leave.
Relocating to her parents’ house, Isabel grapples with the weight of her experiences. The detective, worried for Isabel's safety, recognizes a pattern where those he questions about her case seem to meet untimely ends.
The film culminates in a tense finale where Isabel sneaks her pupil into her family home. In a shocking turn, the child screams about a man, prompting Isabel to react violently, thrusting a knife into her father's stomach. She then sits in a chair, cradling her pupil, who is revealed to be a younger version of Isabel, representing her own childhood abuse. The detective is also present, eventually cradling Isabel as she unravels the haunting memories of her past.
The storyline intertwines the complexities of grief, trauma, and the supernatural, leading to a hauntingly powerful resolution that reveals the vicious cycle of violence and the quest for healing. At one moment in the story, Isabel poignantly reflects on her harrowing experiences:
> "It’s like I’m trapped in a nightmare, and the only way to wake up is to confront my demons."
