The movie opens during a dark night when someone breaks into the Conroy family home,
with six-year-old Ella waking from her sleep. Ella sees that her door is open and no one is
at the end of the hallway, so she gets up to investigate. A presence wanders through the house,
but Ella can only run out of fear to close the door while cursing. When she returns to her bed
she finds a dark figure telling her that she cannot speak. Ella doesn't know who it is,
she can barely see a man with glasses who tells her that she shouldn't curse because
that’s a sin. He mentions her name and she asks him how he knows it, but the man only
tells her that he knows many things. Just when he’s about to tell something important,
Ella wakes up scared revealing that it was all a nightmare. Ella thinks she is safe,
but the man suddenly appears and grabs her by the neck, lifting her out of bed. The girl is losing
her breath and the man asks her about her father. It is then that Ella's father Theodore wakes up
shaken from the nightmare. He just gets up and goes to the bathroom to take a couple of pills to
sleep. The next day Theodore relaxes by his pool while listening to recordings on meditation and
dream control. The recording says that nightmares are ways our minds tend to relax and release
day-to-day stresses. A call interrupts him, and he tells his young wife Susanna that the call is for
her. She recommends him to take a dip in the pool to refresh himself, but he prefers to continue
relaxing. Susanna laughs at the message and asks Theo to pick up Ella that day. He readily agrees,
but she also asks him to pick her up the next day, dashing Theo's hopes of being with his wife. She
thanks him and says she'll get someone else to do it then. Kisses him and leaves laughing over her
phone conversation, with Theo trying to shrug it off and go back to his meditation. Susanna
is an actress and Theo tries to visit her on set but is at first mistaken for her father,
denying him entry when he explains that he is not. Theo has an extremely awkward moment with
the guard while listening to a passionate romance scene Susanna stars in. Theo gets angrier when
they let the coffee guy in instead of him, and so the scene is replayed. When they are finally able
to be together, Susanna apologizes to Theo for the scene, feeling it was a bit over the top. She says
that maybe they didn't let him in because they considered Theo too dangerous and that she'll put
him on the approved list for the next one. Susanna proposes to do hot things in the car that night,
and Theo confesses how much he hated being present during that day’s scene. Still, he proposes that
they should enjoy their time together more, considering finding a place where just the two
of them and Ella can be alone. Soon after, they decide to book a vacation in Wales in a secluded
place that claims to be perfect for relaxation and contemplate. Theo criticizes Susanna's driving,
who isn’t used to European roads, but Ella doesn't feel comfortable during the trip. Ella asks Theo
if since he is older he will leave the world before her mother, but Theo tells her that
he’s not that old yet. After some dark comments Susanna almost crashes the car on the road, so she
decides to switch places with Theo, telling him to talk to Ella about heaven instead. They pull
up to the huge house, and Ella gets excited about how beautiful it is, with the couple admiring how
much better the house looks compared to the internet pics. However Susanna complains that
there is no phone service there, and Theo manages to appreciate how calm and quiet everything is.
As Susanna continues to look for coverage, Theo stresses that the former tenants took absolutely
everything personal from the place. He decides to continue the previous conversation with Ella,
and tells her that when they are all in heaven they can be together again. Before the
conversation gets murkier, Susanna interrupts to tell Ella about her new bed, leaving Theo alone.
At night Ella plays shadow games before bed, but when a strange shadow appears behind her,
her father arrives to wish her a happy night. She tells him there was a shadow just now, but
he thinks she is still playing and turns out her light, unaware that something is lurking nearby.
Theo asks Susanna to talk to the landlord about a problem with the thermostat downstairs, and
although she asks him to do it Theo tells her that the house is reserved in her name, so she’s the
one who should write to him. He regrets being so annoying, but manages to content Susanna before he
sees Ella watching them from a distance. When he approaches her the girl runs off to her room, with
Theo worrying that he has done something wrong. He goes downstairs and tries to figure out how the
lights in the house work so he can turn them off. However, he fails to turn off one particular lamp,
so he leaves it on. Theo goes to another hallway where he gets even more light switches, but as he
uses them he notices that there’s a room whose light won't turn off. Upon entering he realizes
that it’s an office and that the light is from a table lamp. When he turns it off he sees a door
behind him that is still open and illuminated. It is a laundry room that has a polaroid photo
taped to the wall. On close inspection Theo appreciates that the photo is the silhouette
of a person entering a room in the house. He does pay attention and returns to his room,
not noticing that the table lamp turns itself back on. When he returns to Susanna, he realizes that
she has already fallen asleep, even though she was waiting for him a few moments ago to watch
a series. When he wakes her up, he is surprised that she has gone so deep in such a short time. It
shows that it has actually been almost five hours since Theo went downstairs to turn out the lights.
In the morning Theo awakens after restless dreams, finding a note where the girls tell him they went
for a walk. Mother and daughter explore the forest while Theo stays home with his meditation program
using a personal journal. As Theo describes his negative feelings of frustration and anger,
Ella climbs a tall tree worrying her mom. She asks Susanne why her people dislike her father,
and before receiving an answer the girl slips out of the tree, but with Susanna managing to catch
her in time. When they are calmer Susanna explains to the girl that her father was married to another
woman named Caroline years ago before they met. One day Caroline took a bath having taken many bad
pills, and never got out of the tub again. Theo found his wife passed out and couldn't save her,
but now everyone thinks it was him who put her in the tub. Ella asks her if that's true, and Susanna
tells her no, that it's false and that her dad is innocent despite people thinking otherwise.
She tells him that her dad became famous because of his trial, and now many people know him in a
negative way. Theo goes shopping at a small local store, and finds himself annoyed by the slow pace
of the clerk. He fails to understand his English so well, thinking he is Welsh, but the man only
asks him if he is staying nearby at the home of Stetler. Theo tells him that he has no relation
to the owner of the house and that he only found the place on the Internet. Passing him a bill,
the salesman does not give Theo the change but a simple triangle square. He meets a lady by his
car who asks him if he has had any contact with Stetler. Theo tells her that he hasn't even seen
him in person, and the woman comments that Stetler has seen him. On the way home, Theo learns that
Susanna told Ella his backstory, which makes him very angry. He and Susanna had agreed to tell Ella
about it when she was seven, but Susanna tells him that the girl insisted at the time. Theo gets
angrier and berates her about how hard it is to be married to someone who brings the role of actress
into real life, now angering Susanna. The family shares an awkward dinner, with Susanna leaving the
table and little Ella comforting her father and showing support. When Susanna goes to take a bath,
she leaves her phone in the room and Theo takes the moment to dig into her conversations. He sees
an unregistered number, but it's just a message about Ella's dance classes. Finding nothing he
decides to put the phone aside, but thinking there may be something else on her tablet. Theo
tries to make time by chatting with Susanna while searching for messages, finishing before she comes
out of the bathroom. He apologizes to Susanna for all the awkward conversation earlier that
day and they make up. Theo wakes up at midnight because he can't sleep, so he decides to resume
his meditation program. However, as he does so Theo has negative thoughts and doesn't notice
that his reflection in the window remains static as he turns his gaze. He notices how suddenly
there’s a mysterious door where there is supposed to be a bookcase, and when he opens it he sees
stairs leading to lower floors. Already at the basement the scenery changes to a more sinister
and neglected one, looking like some kind of abandoned building. Upon seeing a hallway,
a flash makes it appear that the same photo that was on the wall the night before was taken. Theo
finds a series of photographs of him and Susanna sleeping and panics. Everything gets worse when
he finds Ella's stuffed bunny, thinking the girl has been kidnapped. He finds her in a near room,
but with signs of having been put underwater for a long time. Theo thinks it’s a nightmare so he
forces himself to wake up. The next day he learns that Susanna also had a nightmare, only a little
lighter. He takes her to explore the office and laundry room and explains how last night's dream
went, asking her when it was that he fell asleep. She tells him it was almost immediately, and he
asks if she remembers when he woke up, to which she denies it. They both agree that they hate
the place and decide to leave as soon as possible, even though Ella still likes it. While Susanna and
Ella play outside Theo texts the former, watching from inside the house how she answers the phone.
However Theo notices that Susanna's phone is next to him, confirming that Susanna is up to
something suspicious with a second phone. Going to the office to write in his diary, Theo finds
that it is written "you should have left, now it's too late to leave" and considers that last night
wasn’t a dream. He goes out to confront Susanna and Ella is asked to enter the house. Theo tells
Susanna that he knows about her second phone, asking her if her lover is in the house. She
denies this, but he insists that someone wrote in his diary. They both have an argument but Susanna
can't handle Theo's calm and restrained anger, who claims that she’s having an affair. He tells
Susanna that she will have to leave the place and that he will stay with Ella since she broke the
rules. Before leaving, Theo berates Susanna for being unfaithful and watches her drive off in the
car and cry on the road. Theo and Ella are left alone in the house, with her knocking over a glass
of water as she’s riding around on her scooter. Although he told her to stop, Theo just hugs her
and tells her it's okay, with the girl telling him that she doesn't like being in that place either
and that she has bad dreams at night. He tells her that even though her parents are fighting,
her mother will be back the next day to drive them back in the car. Theo observes something
strange with the water spilled on the floor, so he does an experiment by spilling more. He uses the
triangle square to measure the angles of the wall and floor, perceiving a mismatch. Along with Ella,
Theo notices that the kitchen turns out to be much larger on the inside than on the outside,
something that doesn't make sense. Ella gets cold and tells her father she'll go get her coat. He
sees her from the window and watches how she is now heading towards the exit next to him, but
something strange happens and although Ella goes through the door, she never comes outside. Theo
sees this and decides to look for her thinking it’s all a game of hide and seek. Ella ends up in
the dark hallway of the nightmare while Theo gets lost in the labyrinthic house, entering repeated
rooms and finding extensive hallways. Theo ends up in the office, again encountering the door in
the middle of the bookcase, only now there is a dark hallway instead of stairs to the basement.
The doors close behind him and little Ella finds herself in a room with a bathtub in the middle.
She sees that there is a woman in the tub and that the water is overflowing. She asks the person if
she’s okay, but when the woman moves abruptly Ella is startled and finds a strange old man who scares
her away. Theo manages to hear Ella and catches her up on the stairs, with the girl saying she
was lost in the house. They both decide to get out of there calling Susanna to pick them up, but the
phone has no reception so they have to wait. Theo calls the grocery store clerk and asks for a cab,
but the man tells him there are no cabs nearby. The salesman asks if Theo has already used the
triangle and Theo says yes. Then he starts talking about how before that house there was another one,
and before that, there was even a tower. He tells him that the Devil creates a house to
collect souls, but God always manages to destroy it, only for the dark lord to re-erect a new place
over and over again. The man tells them that their being there is not their problem, so he hangs up,
with Stetler now answering Theo. Father and daughter get dressed to go out at night,
trying to walk to town and just as they leave, Emma sees a silhouette inside the house. Theo
sees it too and they pick up their pace in the dark, encountering animal sounds in the
distance. Despite having walked a lot they realize they were walking in a circle and end up back in
front of the house. Although the girl doesn't want to go back inside, Theo tells her that they
have no choice and that they should wait for her mother there. They both lie down and fall asleep,
but soon after closing their eyes Theo feels the flash of a picture and wakes up. He hears that the
bathtub key is open and as he tries to close it the bathroom doors close behind him, separating
him from Emma. When he opens them, he finds himself in a dark old corridor, which ends with
a bathtub with water overflowing. He’s surprised from behind by the female entity in the tub,
who attacks him and disappears with a flash. Theo runs down the hallway until he reaches the office,
seeing himself writing in his notebook. As his other self leaves, Theo takes advantage and writes
in the notebook the same words from the beginning, warning himself to get out of the house as soon as
possible. He begins to see scenes of his family's arrival at the house as he talks on the phone with
Mr. Stetler, who tells him that he cannot escape. The photo flashes alter Theo's perception of time,
unable to even climb a simple bunch of stairs. When he manages to do so, he enters a room where
he meets Stetler, who tells him that he’s not really who he appears to be and that they are
doomed to be in the house forever. Theo rages at Stetler and starts beating him with his cane,
with the old man telling him that his daughter is doomed for bearing the sins of the father. It
comes a point where Stetler tells Theo how bad it is to be a mirror, revealing that Stetler
is actually Theo himself and that the only one keeping his suffering is him. Theo feels defeated
and meets Emma again, who tells him that despite everything she still loves him. Theo and Emma
leave the house to meet Susanna, but Theo does not greet her, he just leaves the girl inside the
car and kisses her on the forehead. Susanna asks him if he will go too, but Theo knows he belongs
there. He confesses that he actually did let his first wife fall asleep in the bathtub, having had
the chance to save her. He chose not to because of all the hatred he had built up for her. He admits
that he should only have left her when he could, regretting not having made that decision. Theo is
left alone in the house, showing himself to be the shadow that was always there from the beginning.