(NOTE: The story is told in a non-linear fashion. Many scenes in the movie are flashbacks, which are likewise not in chronological order.)
The camera pans along snow-covered landscape and into the home of Mika (Kevin Durand
), who stands near his window while Japanese Kabuki opera plays on a wall-mounted TV screen. As Mika walks downstairs, we can see his home is an expensive luxury house in a secluded area, but with a lot of state-of-the-art security and technology. He looks into the monitor of a desktop computer, which appears to show the view of several security cameras. He slides aside a wall panel to reveal a hidden door locked by a numerical code. Mika enters the code on a keypad and opens the door, revealing a room where a teenage girl (Alexia Fast
) sits, playing a piano and singing. She looks up at Mika apprehensively, and he says he'll think about a request she's made of him: "Maybe; just this once."
A woman named Tina (Mireille Enos
) enters a diner, sitting at a table opposite an unseen woman. Tina didn't show at a planned meeting, which the unseen woman asks if it's because of "her 13th birthday." Tina is living alone in a house and hating it. She misses two people in her life: Matthew and Cassandra, and she misses living.
A bearded man watches a younger man skate at a rink. The skater notices the bearded man, and they both nod in greeting.
The bearded man is Matthew (Ryan Reynolds
), and he drives down a road, picking up a hitchhiker named Paige. As Matthew continues driving, Paige turns her head and notices a photo of a boy and girl posing together in skating outfits, hanging from his dashboard. The boy in the photo looks a lot like a younger version of the young man Matthew recognized at the skating rink.
Matthew drives Paige to her house in town, and watches as she closes the door behind her. Just then he gets a phone call from Tina, asking if he's coming to a meeting with another woman, who's asked to meet both of them. Matthew cites the heavy snowfall as to why he can't make it. Tina tells him he always has excuses. Tina mentions she's noticed a brush like the one her mother gave Cassandra, "in one of the rooms;" Tina works as a chambermaid in a hotel. As she sits, puzzling over the brush, Mika is seen watching her on his computer monitor.
Mika is at work talking with his boss, Vince Grey, a real estate developer. Mika watches Grey give a sales pitch to a man standing near a wall display advertising a new development, and listens with interest as he finds the man is a police detective, Jeff Cornwall (Scott Speedman
). Cornwall asks Grey about his wife, who was the last person seen with another detective named Nicole Dunlop (Rosario Dawson
), who has gone missing. Grey says he'll ask his wife to return Cornwall's calls and speak to him on the matter. He also gives Cornwall two placards advertising a charity ball that recently took place; the placards have a large inset photo of Dunlop in dress uniform. She was keynote speaker at the charity ball.
Dunlop is shown to be the woman speaking to Tina at the diner. Dunlop asks if there's any hope of Tina getting back together with Matthew. Tina says he calls and they talk, a lot, but he never comes to see her in person. Tina believes Matthew is guilty of doing something bad, and she wants him to feel that way.
We see Dunlop interviewing Cornwall for a position in her unit with the Niagara Falls PD. Dunlop's unit deals with stopping child predators and pedophiles. She shows him a video seized from an online child porn site to judge his reaction, telling him their job is never to look away from victimized children. Dunlop introduces Cornwall to the rest of the unit.
Matthew and Tina are watching Cassandra and the boy from the photo, Albert, skate together. Cassandra asks Albert to 'pinky promise' he'll never skate with anyone else. While Tina goes to work, Matthew drives Cassandra to a roadside restaurant, and she lies down across the back seat while he places a dinner order to go for the both of them. The camera pans in on the door, and then Matthew is seen returning to his vehicle-- and his daughter is missing. Matthew's voice becomes more frantic as he runs all about the area, calling her name.
The teenage girl is shown to be Cassandra at her current age; she's Mika's captive, and has been since she disappeared; now eight years ago. Mika is offering her a chance for a few moments' conversation with her father. Cassandra notes Mika doesn't like the idea, and reminds him that he's never told her his name, and she has no idea where the house containing her prison, is. Cassandra has not attempted to escape or contact her parents (she is also able to watch Tina at work in the hotel, on her own computer) because Mika has threatened to kill both Matthew and Tina. Cassandra wonders if it wouldn't be easier for Mika to kill her, now that she's reached young adulthood and Mika is interested in young kids. Mika tells her only that she's still very valuable to him, 'doing exactly what she's doing.'
Dunlop and Cornwall are interviewing Matt three hours after Cassandra's disappearance. He's disgusted and astounded at how closely they pay attention to his first saying her still-current age (nine years) and then shortly after, her soon-to-be-age (ten years) and whether the name of the diner's hostess was Linda or Lesley.
Tina is cleaning a bathtub while at work, and sees a skating trophy in the room; one looking a lot like one that Cassandra and Albert won together as kids. As Tina stares tearfully at the trophy, Cassandra speaks into a microphone about when she won it. Mika, listening in, commends her on the performance, but asks her to repeat it 'with less self-pity.'
Tina is brought to the station. She becomes hysterical as Matthew tries to talk to her about Cassandra's disappearance. She hits him several times, and doesn't resist as he grabs on to her and holds her. Dunlop takes Tina into a room to speak to her alone. As Dunlop speaks to Tina, Cornwall baits Matthew about an assault charge tied to a barroom brawl over Tina when Matthew was 18 years old and Cassandra was a baby. Because of this, he quit school, started working, and now, nine years after that, his landscaping business is about to fail and he's on the verge of bankruptcy. Cornwall also questions why Cassandra would be resting in the back of the cab when Matthew was buying her favorite dessert pie for her with dinner. Cornwall finally drops a rude and crude bomb about the possibility of Matthew "loaning" Cassandra to a demented pedophile for a few days in return for a lot of money. Outraged, Matthew tries to hit Cornwall, but the detective shoves him to the ground. As Matt leaves, Dunlop admonishes Cornwall over his behavior.
We see Dunlop meeting Tina in the diner again; Dunlop telling Tina that she doesn't excuse the way Cornwall acted toward Matthew, but trying to explain it from Cornwall's point of view. Tina still hates it, defending Matthew's love of Cassandra. She leaves the diner, very upset.
Mika again watches Tina at work. As she changes bedsheets, she finds a ring box on the bed, which contains a baby tooth. Tina breaks down and cries as she suspects it's one of Cassandra's baby teeth. Meanwhile, Cassandra makes a recording about it. As she speaks into the microphone, she finds a way to slip something into the narrative; part of a word play between she and her father the day she disappeared. She smiles to herself.
Tina meets with Dunlop in her office. Dunlop asks Tina about her relationship with Matthew. Tina says she can hardly look at him without seeing their daughter and saying terrible things; he didn't show up for this meeting because he was sure Tina would scream at him in anger; something Tina admits she would probably have done. It's clear by this point that Matthew is still suspected of at least negligence in Cassandra's disappearance, and even Tina holds him responsible; thus their estrangement and separation.
Dunlop takes Tina to a back room where Cornwall sits at a computer. Dunlop and Cornwall tell Tina about some of the work Cornwall does, posing as a pedophile to study footage of internet chat networks where child molesters trade in images and live video feeds of children being abused, in hopes of tracking down the perpetrators. Cornwall believes he may have seen some images of Cassandra among the feeds. The pictures look very recent, showing what Cassandra is believed to look like in the present, which Tina understands, with great relief and delight, means her daughter is most likely still alive.
Tina studies the images and says that she believes the photos look like Cassandra. She calls Matthew and tells him about it. She says that Dunlop and Cornwall told her that in the images, Cassandra appears to be speaking to another girl, younger than Cassandra would be in the present. Tina puzzles over something else Dunlop and Cornwall told her: that Cassandra is like a welcoming face on a gateway... to a ring. Tina's voice goes quiet as she figures out what they meant: Cassandra is being used to lure other, younger children to the attentions of Mika and other child molesters. This enrages Tina and she again cuts into Matthew with her belief that he is responsible for 'losing' their daughter.
Cassandra is reading aloud a poem, which Mika tells her is from an opera composed by Mozart. Cassandra asks how it's supposed to help bring in other kids, and he says it isn't; it's part of 'story time.' Disturbed, Cassandra turns to her piano and tries to comfort herself by playing and singing.
Tina, at work, finds another memento of Cassandra in one of the rooms under her charge: a play teacup and saucer. It's clear by now that both Mika and Cassandra are able to watch her regularly on their computer monitors via some kind of camera feed, and that Mika has been leaving these items to torment her.
Dunlop's team are photoshopping an image of her during her adolescence, to optimize her attractiveness. They catch the attention of Willy (Ian Matthews
), a pedophile to whom Cornwall has been talking via internet chat, posing as a girl. Willy bites at the bait; he asks "Nikki" if they can meet.
Dunlop sits at a coffee shop, her hair and the hood of a bubble-gum pink sweatshirt obscuring her face. Willy walks in and initiates contact. As soon as Dunlop looks up at him, he can see she's much older than the photos indicated, and he tries to make a break for it, but Dunlop's men are waiting and they swiftly arrest him.
Dunlop and her team come to a good deal of acclaim and prestige for their work in the Niagara area, and she's interviewed by the local TV press. Dunlop and Cornwall are seen watching this on the TV news station, and it's seen they've entered a romantic relationship.
Mika also sees the news report, and goes to see Willy in prison. He insists that only the first ring has been cracked, and the 'hub' he operates is safe. He tells Willy to deny all accusations and refuse any deals offered him. Willy insists he will only do this if Dunlop is punished for setting him up. Mika says this is infeasible, but Willy insinuates that he will turn rat if his demand is not met. He wants her buried, but alive, and made to tell all her stories.
Cornwall is also doing another sting operation: his young niece, Jennifer, is web-chatting with Cassandra. As soon as Cassandra tells Jennifer that she's willing to meet with the girl and show her how to write a note for the tooth fairy, Cornwall's head snaps up and he believes he's ready to hit paydirt. But suddenly Dunlop arrives, earlier than expected, and even when Cornwall tells her that his brother (Jennifer's father) knows of Cornwall's plan and has given permission, Dunlop gets very upset. Mika sees Dunlop come into view of Jennifer's webcam, recognizes her, and immediately terminates the chat connection. However, a green LED remains lit, showing that Mika can still see and hear everything happening in the room via Jennifer's webcam. He watches and listens as Dunlop tears into Cornwall over the sting, and using a young girl as bait, potentially endangering her. Mika also learns that Dunlop's unit knows what Cassandra is being used for. Most important, he overhears Dunlop telling Cornwall she no longer wants him to accompany her to an event happening that night; she's going alone.
Cassandra also overhears the whole argument between Dunlop and Cornwall, and she starts to cry.
Dunlop arrives via taxicab at the charity ball honoring her. She's wearing a pink evening dress and looks beautiful. She's met by Diane Grey, wife of Mika's boss. Dunlop has been given a seat at Mrs. Grey's table. Mika comes over to say hello to Mrs. Grey, and he plays along as she introduces him to Dunlop. Mika now has a perfect cover as a known acquaintance of Mrs. Grey.
A mysterious woman with long dark hair enters the ball. She takes a powder out of her purse and puts it in her drink as she listens to Mrs. Grey introducing Dunlop as keynote speaker of the charity ball. The only empty seats are Dunlop's (she's on stage) and another at the same table. As Dunlop is speaking, the mysterious woman sits at Dunlop's seat and puts her drink down. Mrs. Grey whispers to the woman that the seat is taken, so the woman moves to the other empty seat... discreetly taking Dunlop's drink instead of the one she just put down right beside it.
Dunlop's speech earns a standing ovation and a high number of pledges. Seated again at Grey's table with Grey, Mrs. Grey, Mika and the mysterious woman, she talks about the technology she and her unit work with; something Mika takes the opportunity to ask her about. In the meanwhile, Dunlop has finished her drink and Grey has poured her a second. The powder starts taking effect.
The mysterious woman helps Dunlop downstairs and out of the center, and offers her a ride. She helps Dunlop into a limousine and sits beside her in the back. There, she pulls off a long dark wig, revealing short, blonde hair underneath. The woman is Mika's accomplice, Vicky (Christine Horne
). Dunlop realizes she's been drugged and is in serious trouble, but can do nothing as Vicky crades Dunlop over her lap and watches her slowly black out.
Matthew is delivering a shipment of evergreen saplings to a work site, only to find the foreman has sent everyone home due to the snowstorm. He tells Matthew that there's a roadsite motel a very short distance down the highway where he can spend the night; if he brings a receipt back to the camp the next day, the foreman will reimburse him the cost.
But when Matthew checks out the next morning, he finds the trailer has been stolen, and one of the trees lies on the ground near his truck. When he happens to look in the direction that the top of this tree is pointing, he sees a number of the trees stood up in the snow along the road, forming a trail. He gets in his truck and follows it. As he reaches the end of the trail, where a barricade has been placed, he fails to notice a camera in the top of a nearby tree.
Matthew follows the last couple of trees on foot to a clearing where a young woman stands near the trailer. It's Cassandra. Matthew is overcome with relief and joy as he hugs his daughter. Cassandra tells him cryptically that the people who took her arranged for this meeting because she's precious to them, but she only shakes her head silently when he tries to press her to say who these people are. Matthew doesn't understand when Cassandra begins repeating bits of the conversation they had in the truck just before her disappearance, saying a promise was made, and asking if it was kept-- a cryptic reference to whether Albert kept his promise never to skate with anyone else. Finally Cassandra says the visit is over, and she has to go, and Matthew has to forget her. He refuses, grabbing her in a tight hug and insisting he's taking her home. Mika, coming out of hiding behind the trailer, aims a rifle and fires a tranquilizer dart into Matthew, knocking him out. Cassandra doesn't resist as Mika helps her to her feet and leads her away.
Mrs. Grey meets with Cornwall to discuss Dunlop's disappearance. The only lead is the mysterious woman who showed up at the ball. Mrs. Grey mentions she took the only empty seat at the ball-- the seat that Cornwall was supposed to occupy until Dunlop decided not to bring him. Cornwall lets this slip, and Mrs. Grey asks if the mysterious woman knew this. She thought nothing suspicious about the mystery woman offering Dunlop a ride, because Dunlop needed one and was traveling alone.
Driving down the road, Matthew figures out why Cassandra was repeating snippets of their conversation from the day she vanished; she was making references to Albert. He understands Cassandra wants him to pay attention to Albert; hence why he watches Albert practicing at the skating rink.
Dunlop awakens to find herself locked inside an empty van with heavy wire grates preventing her from escaping via any of the windows or doors; a van meant to remind her of one she had talked about having to sleep inside on her 14th birthday when she had been homeless and alone. Mika falsetto-sings the notes of an opera that Dunlop can hear through strategically placed speakers. Although Dunlop cannot see it from her vantage point, the van imprisoning her is in a garage or large storage room.
On duty at work again, Tina find yet another memento of Cassandra's childhood; a series of pinwheels attached to the railing of the balcony for one of the hotel rooms. Tina breaks down and starts to come apart.
Mika torments Dunlop further by pressing her to start talking more about her stories, including how she had to sleep in the abandoned van when she was 14. He warns that if she doesn't talk, he might stop returning, and leave her to die of thirst and starvation.
Tina has called Niagara police. She's with the hotel manager in the room where she found the pinwheels, and Dunlop is studying the room. An air vent catches her attention, and she pries off the cover to reveal a hidden camera.
Dunlop's men have found an elaborate series of hidden cameras in all the rooms in the hotel where Tina works, and are discussing why they were put there. They theorize that Tina may have been watched for a long time, even though the mementos of Cassandra have only started showing up relatively recently. They theorize that people involved in the child-abuse network pay to watch the footage of a missing girl's mother gradually freaking out.
Matthew arrives home where Tina waits with Dunlop and Cornwall. When they tell him about what's been going on at Tina's job, Matthew only becomes angry, thinking they suspect him. He challenges Dunlop to arrest him if she thinks he's involved in any criminal activity. As Matthew leaves, he finds Cornwall taking pictures of the inside of Matthew's truck, which is still decorated with many items related to Cassandra's childhood; including the picture of her and Albert, and the blanket Cassandra had lay on when she was taken. Cornwall asks why the truck resembles a shrine. Matthew's only response is a punch that knocks Cornwall to the ground, before Matthew gets in his truck and storms off.
In her room, Cassandra is telling Mika she needs to feel new experiences, now that she can't watch her mother anymore. She reminds Mika of a particular story she told him about when she won the trophy and showed it to her mother, how Mika said it was the most moving story she told him. Cassandra suggests making it better. Interested, Mika asks her how.
Vicky goes to the skating rink where Albert still practices, and poses as a journalist writing an article about missing children and the people involved in their lives before they disappeared. She tries to ask Albert about his time skating with Cassandra, and whether he kept the trophy they won. Albert is hostile to this questioning and refuses to speak to Vicky. As Vicky leaves, Matthew, seeing Albert demand that Vicky leave him alone, goes to him and asks why Vicky was bothering him.
Matthew begins tailing Vicky and sees her van pulled up beside a small roadside diner. He calls Dunlop's office and tells Cornwall about the van, and that he's going to secrete his cell phone in it. He gives Cornwall the phone's number, which will allow others in Dunlop's team to track it via GPS. Although Cornwall is still cynical toward Matthew, he and the team find they believe him enough to start a track on his phone. Matthew slips his phone into the large spare tire mounted on the trunk of Vicky's van.
Matthew begins acting in a disruptive and hostile manner to the diner manager in order to make him call the police. Finding a poster of Cassandra, he takes it and sits at the table where Vicky and Mika are talking. He is careful not to voice his suspicions about them, but shows them the poster and identifies himself as Cassandra's father, and that he is displeased with police having dragged their feet on the investigation for so many years. Vicky acts compassionate toward Matthew as she and Mika try to accommodate him. The diner manager tells Matthew that the police are on their way. Matthew leaves, and Vicky suddenly notices that in the distraction, he lifted her cell phone.
Mika and Vicky pursue Matthew, ramming his van and shooting at him, but he makes it back to the diner where a police van has pulled up, forcing Vicky and Mika to leave. Dunlop's team tracks the van and discovers where Mika lives.
Dunlop's team storms Mika's home. Mika had been leading Cassandra out of her room. They hear the police, and Cassandra tries to scream. Covering her mouth, Mika forces her back into her room, but is unable to lock it before Dunlop's team arrives. Vicky shoots Cornwall, but his vest protects him; he's wounded but not badly. Vicky is gunned down and killed. Mika begins walking toward the officers with a hostile look. When he refuses to halt on command, they shoot him. An officer demands to know where Dunlop is. Mika only says that she's in a van where she had her 14th birthday, before he dies.
Cassandra is rescued, and has a tearful reunion with her parents at the police station. Tina even hugs Matthew with one arm as she embraces Cassandra in the other.
Cassandra and Tina visit Cornwall as he recovers in the hospital, and he talks about Dunlop's meetings with Tina, how Dunlop benefited from them as well as Tina.
Matthew clears all the mementos of Cassandra's childhood, out of his van.
Police find their way into Mika's garage and find the van in which Dunlop is held prisoner, rescuing her.
Cassandra steps onto the ice in the skating rink and starts to skate, and she smiles.