In the film set in 1979, Alice Gould de Almenara is admitted to a psychiatric hospital under mysterious circumstances. She is left at the gates by a man and is soon interrogated by Dr. Ruipérez, who reads a letter from Dr. Donadío. Alice firmly claims that she has been "legally abducted" by her husband, Heliodoro, with the purpose of seizing her wealth. Inside the facility, Dr. Castell introduces Alice to the staff, and she begins her own investigation into the death of Damián García del Olmo, the son of Dr. Raimundo García del Olmo. As her inquiry progresses, she becomes familiar with key characters, including Ignacio Urquieta and the twins, Rómulo and Remo, as well as the Gnome, a sexually abusive man protected by the Elephant Man. The Gnome, who shows hostility towards Rómulo, appears to hold a significant grudge. Alice participates in therapy sessions led by Dr. Arellano.
Throughout the movie, the storyline unfolds along two timelines. The primary timeline narrates Alice’s experiences inside the hospital, while a secondary, darker timeline takes place on a rainy night. In this secondary sequence, chaos erupts with a fire and riot, culminating in the discovery of a corpse in one of the cells. During this night, Urquieta is initially accused by the authorities but is later cleared of suspicion following forensic scrutiny.
In her interactions with Urquieta, Alice questions whether he suffers from schizophrenia, a condition she believes might explain Damián's killer’s mental state. She notices that Urquieta has a deep-seated fear of water, which becomes more apparent as the story progresses. Urquieta confesses that Damián had conflicts with the Gnome, hinting at underlying tensions amidst the chaos.
Alice’s suspicions intensify after she is assaulted in the forest by the Gnome. When she awakens, she finds herself chained to a bed, and Dr. Arellano informs her that she is the presumed killer of the Gnome — although she struggles to recall what exactly happened after the attack. Determined to uncover the truth, Alice meets Director Samuel Alvar, claiming she has previously exchanged letters with him through instructions from García del Olmo. However, Alvar denies any such correspondence. Her frustration peaks as she attacks Alvar and attempts to escape, only to be sedated once again.
Back inside the hospital, Alice confides in Dr. Castell about her suspicions regarding Damián’s murder. She requests a meeting with the medical council, explaining how García del Olmo provided her with guidance to infiltrate the institution by feigning mental illness, and how she managed to convince others of her supposed paranoia. She reveals that she was motivated by a desire to uncover the truth about her stepson’s death, and she believes Herrador, her husband, only married her for her money.
Meanwhile, Alvar claims that Alice was committed at the recommendation of Donadío, acting on behalf of Heliodoro. Alice admits that she deliberately pretended to have a mental disorder, and she explains her plan to interrogate the staff and uncover what truly happened to Damián. She recounts how García del Olmo gave her instructions that required her to appear paranoid and how they managed to have Donadío attest to her condition, and Heliodoro sign the authorization for her detention.
As the story thickens, Alice reveals that Heliodoro tried to poison her, and after a seizure, he found her hiding the poison. Corroborating her story, she says she faked her persona as a private investigator to get closer to the truth. When she attempts to identify a man she believes is García del Olmo, she is subjected to electroshock therapy and moved to the Cage, a secluded part of the hospital where she becomes convinced she is being framed by Heliodoro, who, she suspects, hired someone to impersonate García del Olmo.
In her unwavering quest for answers, Alice plots to set fire to the facility, believing it will uncover the false identities and motives of those around her. Urquieta helps free the other patients during the chaos, and she discovers a dead twin, which ties back to the secondary timeline. She encounters the forensic doctor and learns of Rómulo’s death, impersonates her, and finally uncovers the identity of the actual killer — the Elephant Man.
The climax revolves around a meticulously convened medical council. Alice’s evidence leads some to believe she is innocent, while Alvar decides to withhold his vote, unsure of her guilt. Ultimately, most of the doctors clear her, and Donadío is permitted into the room. To her shock and dismay, Donadío turns out to be the man she identified as García del Olmo, revealing a chilling conspiracy at the heart of the hospital’s dark secrets.
Throughout this haunting journey, the movie explores themes of deception, mental illness, and the quest for truth, interwoven with suspense and psychological intrigue. The film’s rich narrative structure, dual timelines, and complex character interactions paint a vivid picture of mystery and paranoia, keeping viewers captivated until the very last revelation.
