In 2011, Madrid becomes the backdrop for a chilling, methodical experiment led by Professor Fuentes Fuentes. He binds five medical students to chairs and outlines a disturbing challenge: push the limits of the mind, and demonstrate the power to suppress or conjure real symptoms. He selects José Aguas as a cocky volunteer, and in front of the group he produces an emergency cabinet and a penknife, slicing José’s arm to prove that the mind can command the body to bleed or to halt the bleeding. The implication is stark: if José cannot control his body, he will die from a wound that seems cosmetic. The room erupts in panic as the students watch, and Belén warns Fuentes to stop and tells him she’ll report him to her father, but no one can stop the dramatic moment.
Fuentes insists the mind can not only mask symptoms but also manufacture them. To prove it, he reveals a surgery bag filled with pig blood attached to the chair; when he “cuts” José, the bag begins to bleed slowly, while José himself remains seemingly unharmed. A tense struggle breaks out as José tries to strike out at Toni, but the others hold him back. Fuentes gathers his papers, left with a stark reminder for the would-be surgeons: stay calm, stay collected, and learn to handle pressure in the future.
After the demonstration, Ángela chases Fuentes down, unsure how the promise of no final exam for his guinea pigs squares with the threat of losing her grant. Fuentes praises her composure but hints that the price of knowledge may be high. He speaks of a nearby ghost town called Susurro, its legend tied to salt mines and to a physician named Dr. Matarga who, according to local lore, haunted the living long after death. Ángela is skeptical but curious enough to propose a scientific study to settle the question once and for all. If she can prove Susurro is nothing more than perception, her future may be secured; if not, the experiment could redefine her path.
To pull this off, Ángela recruits friends and colleagues, and even asks her sister to lend a hand. She sends Diana—her younger sister—to bring along a blue van they can use to transport equipment to Susurro. The familial tension behind their split lives surfaces in a flashback: a younger Diana and Ángela, as children, playing with their dollhouse while their executive father, the presence of Padre, looms over them. In the present, the sisters’ relationship remains strained, with Diana hurting herself in a private moment, a ritual underscoring the family’s deep wounds that have festered over the years.
As a plan forms to investigate Susurro, the group—[Belén], [José], [Ángela], Carlos, and Diana—meets outside a seaside club and then heads toward the abandoned salt town. Their journey begins with the bleached, empty streets of Susurro, where the group intends to spend the night inside an old church—believing it will offer protection from vengeful spirits. The trip is rocky from the start: the blue van grinds along, a train of nerves and nerves of doubt among the six of them. They split into pairs and start exploring—the old meat-processing factory, the mine, and nearby ruins—hoping to capture something real on tape.
In the mines, Diana falls into a trance, listening to distant screams that Toni suggests come from those with traumatic childhoods. The group’s attempt to prove a ghost story turns personal as Diana sees the figure of Dr. Matarga and remembers painful memories of the past. The discovery of Matarga’s cruel history—his murders, his tortures, and the town’s habit of sealing him in the salt mines—adds a creeping dread. When Carlos, who is under Diana’s care, is attacked by Matarga in a terrifying confrontation, the night devolves into a fight for survival, forcing the group to confront their own past traumas.
The night spirals into a brutal sequence of hauntings and violence. Diana’s memories fuse with Matarga’s malevolence, and the line between memory and possession becomes blurred. José records farewell messages for his family as danger closes in. The church becomes a stage for a grim finale: [Ángela] must confront the truth about her sister and their father’s abuse, while Matarga’s presence seems to possess Diana’s body and mind. The group discovers a hidden corridor linking the torture room to the salt mines, a discovery that exposes how the past still bleeds into the present.
Tragedy stacks upon tragedy as Belén is killed in a brutal encounter, and [Diana] and Matarga merge in frightening fashion, to the point where Diana appears to attack Toni with a voice that is not her own. The group realizes that what they are seeing may be more than possession—it could be an authentic haunting that refuses to be dismissed as superstition. In the church, the camera reveals the truth: Jose’s last moments with Diana, and Diana’s sudden, dangerous transformation under Matarga’s influence.
The aftermath sees [Ángela] surviving, albeit gravely wounded, and returning to a desolate oil station at the border of the town. She contemplates the unsolved questions: what exactly lies behind the memories that torment her, and how much of what happened can be proven by science? A conversation with Fuentes—now distant, practical, and weary—leaves Ángela with a single, heavy reminder: memory can be a burden that never truly ends. He offers a final envelope, containing her father’s watch, suggesting that the truth may be buried within personal artifacts and long-buried pain.
In the closing, a doctor, voiced with Matarga’s presence, confronts Ángela with a stark choice: remembering what happened will haunt her for life. The envelope’s contents and the watch become tokens of a burden that cannot be easily laid to rest, leaving Ángela to carry the weight of her sister’s fate and their family’s history as she moves forward.
Throughout, the story balances clinical curiosity with the cruel, unsettled energy of a haunting that refuses to be neatly categorized as either science or superstition. It is a meditation on memory, trauma, and the fragile line between what the mind can heal and what it can resurrect.
