The movie begins in 1975 in Spain, where a group
of kids in gray outfits are playing on the large grounds of an orphanage.
The management gets a call from a couple interested in adopting one of them, and since the paperwork
is completed, Laura will start a new life with her parents and leave her friends behind forever.
Thirty years later, Laura, with her husband Carlos, and son, Simon, returns to the building
that was once her home.
She decides to reopen the orphanage and provide care for special children, just as the orphanage
took care of her.
One day, while Simón is playing around their home, he tells his parents about his two invisible friends,
Watson and Pepe.
Laura finds this somewhat worrisome, but Carlos believes Simon is simply lonely and bored.
During their first week after moving, Laura decides to take Simon to the beach, eager
to show him the lighthouse that used to shine all night when she was a child.
While she collects seashells, Simon wanders into a nearby cave and engages in a conversation
with someone inside, asking for their name.
Curious, Laura interrupts and inquires if he's speaking with his invisible friends,
and then Simon surprises her by stating that it's a new boy.
After guiding Simon out of the cave, Laura sneaks inside, but discovers no one there.
On their way home, Simon uses seashells to create a path, hoping his new friend can follow
it and join him for playtime.
The next day, an elderly social worker named Benigna arrives at the door, seeking to speak
with Laura regarding Simon.
Her peculiar behaviour keeps steering the conversation towards the house rather than
addressing the main purpose of her visit.
When questioned, Benigna reveals details about an experimental program that could potentially
assist with Simon's condition.
It is then revealed that Simon has HIV, and, on top of that, he is adopted, but he is unaware
of both facts.
Laura promptly declines the offer, stating that her husband, being a doctor, is well-informed
about the available treatments for Simon's illness.
She insists that Benigna leaves immediately, as she doesn’t want Simon to learn about
his condition and adoption in this manner.
Once the woman departs, Laura locks the file in her kitchen drawer, and hides the key.
The situation takes an eerie turn when Laura hears a mysterious clanging sound emanating
from her shed at night.
Curiosity piqued, she ventures outside to investigate, only to be confronted by an astonishing sight:
Benigna, despite being asked to leave, is still in the house.
The unsettling lady quickly flees, never to be seen again.
Laura then seeks Carlos' assistance in locating her, and the husband reassures Laura by saying
that if the woman reappears, they will call the cops.
The strangeness of the house persists, as Laura awakens to discover some seashells scattered
at her front door.
But the mother does not pay much mind to it, thinking that Simón may be behind it.
Adding to the eerie ambience, Simon engages in unsettling conversations.
He asserts that he won't grow up like his six newfound friends, who are all kids just like him.
Initially, Laura dismisses Simon's conversation, but her concern deepens when she witnesses
him painting the children, one of whom wears a sack over his face.
Curious, Laura inquires about the children, and Simon reveals that they hold treasures
for the game they play.
In this game, they steal something you love, and you must search for it by following clues.
If you succeed, they grant you a wish.
Simon informs his mother that he has coins he intends to use as treasures to start the game.
Playing along, Laura examines the coin box with Simon, only to discover baby teeth instead.
Simon insists that the game has already begun and his friends have already taken his coins.
The two of them spend a significant amount of time rummaging around their home.
As Simon follows the clues, he eventually discovers a key that he instinctively knows
unlocks the kitchen drawer.
Opening it and digging through the files, he finds his missing coins, much to Laura's
anger since she intended to keep Simon away from that file.
In response, Simon erupts in anger and reveals that he knows Laura and Carlos are not his birth parents.
He tells his mother that one of his new friends, Tomas, told him that, and that he will die soon.
Laura is stunned by this revelation, yet she and Carlos dismiss the existence of any entity.
Despite their constant reassurances that Simon is not going to die and that they will take
good care of him, Simon continues to perceive it as a lie.
The next day, a party is arranged for the orphanage's opening to welcome the special kids.
While everyone gathers downstairs, Simon persistently urges Laura to see the tiny house he discovered
belonging to Tomas.
When he insists on seeing Tomas' house, Laura slaps him in anger, but she instantly regrets
her actions.
The mother then leaves Simon in his room, and proceeds downstairs to attend to the guests.
Unbeknownst to her, an uninvited guest lurks among them, a boy wearing a sack over his
face, resembling the character Simon had drawn in his painting.
As Laura returns inside to console Simon and bring him to meet the guests, the boy is nowhere
to be found, and then she is confronted by the same masked boy.
He forcefully pushes her into the bathroom, causing her hand and back injuries.
Laura managed to get a piece from the sack when she tried to uncover the boy's face.
Eventually rescued by Carlos,
Laura thoroughly searches the entire house, including the storage room beneath the stairs,
but Simon cannot be found.
After keeping the heavy rods back in the storage room, she proceeds to check the garden, and
even the beach, where she finally spots a boy standing near the cave.
Unfortunately, due to a foot injury, she is unable to walk.
Carlos, who has been following her, contacts the authorities to inspect the cave thoroughly.
However, the rescue team fails to uncover any trace of Simon.
At the hospital, Laura is introduced to Officer Pilar, who gathers crucial information about
the recent intruder, Benigna, and the events that took place in Laura's house.
Pilar reveals that no social worker is registered under Benigna's name, hinting that Simon might
be kidnapped by her.
The devastated Laura is currently bound to a wheelchair after an injury in the sea, so
Carlos entrusts his medallion to her as an expression of comfort.
Later that night, Laura wakes up to mysterious noises coming from the hallway.
She hears a clanging sound from Simon's bedroom, but when she enters the room, there's no one,
except a doll left on his bed.
Six months have passed since Simon's disappearance, yet Laura firmly believes he is still alive.
Despite her scepticism regarding his imaginary friends, she now suspects they were responsible
for his disappearance, and can sense their presence within her house.
However, her claims are dismissed by everyone, including Carlos.
One day, on her way home from seeing a psychiatrist, Laura spots Benigna crossing the street with
a pram.
But before she can approach her, a tragic accident occurs as a truck collides with Benigna,
resulting in her eventual death.
At the accident scene, Laura discovers a doll resembling the masked boy.
As she approaches Benigna to retrieve her necklace, the old woman briefly comes back
to life, filling fear in everyone present.
Following Benigna's demise, the police conduct a search of her residence, and uncover photographs
and videos revealing her previous employment at the orphanage during Laura's time there.
It is revealed that Benigna had a son named Tomas, who she kept hidden from the world
due to his facial deformity.
Tragically, Tomas was found dead on the beach after Laura's adoption.
A confession from one of the orphans disclosed that they had played a prank on Tomas.
They ventured into the cave with him, and removed his mask to see if he would come out,
but the embarrassed boy never emerged from his hiding place, and was drowned by the rising tides.
Laura then says that she saw him on the day of Simon's disappearance, but none of the
other guests recalls encountering a child with a sack over his head.
Later that night, as Laura prepares to sleep, her bedroom door unexpectedly opens, and Carlos enters the room.
As she is engaged in an emotional conversation about Simon, she notices a shadow beneath
the door.
But her shock intensifies when the figure that walks through the door turns out to be
Carlos himself.
This realization leaves Laura deeply unsettled, as she has been conversing with an unseen
presence for the past ten minutes.
Convinced that something or someone is present in their house, she reaches out to an exorcist
for assistance.
After recounting her story, the man recommends that she consult a medium named Aurora.
Desperate to do anything to find Simon, Laura readily agrees to the suggestion.
However, Carlos remains sceptical about the entire situation and contacts Officer Pilar,
urging her to join the session with Aurora.
As the system operator sets up cameras and microphones, Aurora sits in a room, holding
a doll associated with the orphanage's history.
As psychic summoning begins, Aurora hears the sounds of children.
The noises grow progressively louder and clearer, reaching a point where Laura and the others
can hear the children's screams.
When Aurora enters the room, she is confronted by the distressing sight of the children,
who repeatedly claim that someone is attempting to kill them.
At Laura's request, Aurora even inquires about the presence of Simon, but no response is received.
After the session, Aurora explains to everyone that what she witnessed in the room appeared
to be from an older time, but due to the darkness, she could not see Simon specifically.
She describes how traumatic events can leave behind knots that connect different timelines,
and those who are close to death are often more receptive to such messages.
Despite Aurora's insights, Carlos dismisses it as a mere sideshow trick, and insists that
the team leave.
Before departing, Aurora advises Laura to trust her instincts and determine how far
she is willing to go to find her son.
Later that night, Carlos decides to leave, convinced that Aurora's abilities to communicate
with the deceased cannot offer them any assistance.
Although Laura allows Carlos to depart, she is unwilling to give up until she discovers
Simon's whereabouts.
The following day, Laura bravely enters the house, determined to communicate with the
unseen children.
Suddenly, the window behind her breaks, allowing her to see what's hidden inside the bench.
She discovers her fellow orphans' names written on the floorboards, and among the children's
dolls, she finds a picture of herself and Simon, leading her to believe that the children
are playing a game with her.
Embracing the challenge, she follows the cleverly placed clues taken from her belongings, ultimately
leading her to a doorknob.
The final clue directs her to the shed, where she discovers Benigna's brooch.
On further exploring the place, she stumbles upon a small locked door.
To her horror, she uncovers five sacks filled with human bones.
Shocked and devastated, Laura investigates closer, realizing the bones belong to her
orphanage friends.
The name on the clothes and leg braces of one of the orphans confirms their identities.
The police are called, and Laura finally comprehends the reason behind Benigna's visit to the shed
after three decades.
Benigna poisoned the children’s meals and killed them for having caused Tomás's death,
and hid their remains in the orphanage's coal shed.
Laura explains her theory to Carlos, who cannot grasp the situation and refuses to spend another
day in the orphanage, but Laura insists on two more days to bid farewell.
Once Carlos departs, Laura takes action, washing old bed sheets, rearranging furniture to make
the orphanage look as it did thirty years ago, and hoping for better communication with
her childhood friends.
Disguised as a caretaker, she calls them for lunch, but receives no response.
Driven by desperation, she initiates one of her favorite games from before, a hide-and-seek game.
To her astonishment, the children react this time, and she manages to see them.
Determined to uncover Simon's whereabouts, she follows the kids to seek answers as they
run away to hide.
Led by one of the children, Laura is guided to a small storage room beneath the stairs,
where she finds a hidden door.
Remembering a doorknob she had discovered earlier, Laura bravely opens the door and
descends into the depths, which lead to an underground room.
Inside, she comes across a wall adorned with photographs of the orphans, including Tomas
and Benigna, and we can assume this is where Tomás was kept when he was alive.
Finally, her search reaches its conclusion when she discovers Simon concealed behind
a curtain alive.
However, the atmosphere abruptly shifts, and the blanket she had been holding with Simon
slips from her grasp.
As she turns around, her gaze lands upon a broken railing, and a lifeless body on the floor.
To her utmost shock, it is Simon himself, his body dehydrated after a considerable period
since his passing.
It is revealed that on the day of the party, Simon insisted that he and Laura go to Tomas'
house, which was actually this secret room.
After Laura left him upstairs, Simon went to the room by himself.
Tragically, while searching for Simon, Laura returned the scaffolding that had fallen out
of the closet, and the scaffolding actually blocked the door to the room, trapping Simon inside.
Simon was actually trying to escape that night, which is why there were strange and
crashing noises, but in doing so, he fell down the stairs and broke his neck.
Overwhelmed with guilt, Laura returns Simon's lifeless body to the children's room, and
thinks about why she hasn't received a wish despite succeeding in the game.
Consuming an excessive amount of sleeping medication, she holds Simon close just as
she does with Carlos' medallion, slowly succumbs to unconsciousness.
Sometime later, the mother is awakened by the luminous glow emanating from the lighthouse.
To her surprise, Simon nestles in her arms and miraculously returns to life.
Simon tells Laura that his wish was for her to stay and take care of the orphans.
All of a sudden, the children, including Tomas, now brimming with joy and excitement, draw
near to Laura, enveloping her in their embrace, a long-awaited presence they had yearned for
throughout the years.
In an unexpected twist, the scene transitions to Carlos standing outside the orphanage,
tenderly placing flowers on the graves of Laura, Simon and the orphans.
As the movie ends, another suspenseful moment arises when Carlos discovers the medallion
that he had given to Laura.
Just as curiosity ignites, the door slowly opens, prompting a smile to grace Carlos'
face, and we're all left wondering what's beyond.