Catherine and David, she a doctor, he a professor, are at first glance the perfect couple. Happily married with a talented teenage son, they appear to have the perfect life. But when David misses a flight and his surprise birthday party, Catherine's long simmering suspicions rise to the surface. Suspecting infidelity, she decides to hire an escort to seduce her husband and test his loyalty. Catherine finds herself 'directing' Chloe's encounters with David, and Chloe's end of the bargain is to report back, the descriptions becoming increasingly graphic as the meetings multiply.
In Toronto, gynecologist Dr. Catherine Stewart is at a crossroads in her life. Her teenaged son, music student Michael Stewart, no longer confides in her, she not even knowing that he is sexually active until she catches him in the act. Michael does talk to his father, college music professor David Stewart, who in turn tells her nothing about what is going on with Michael. Although Catherine still loves David, the romance has largely deserted their marriage. She stumbles across some evidence, albeit circumstantial, that David is a chronic philanderer, the most recent case taking place while David was on a speaking engagement in New York City. To find out if her suspicions about David are accurate, Catherine decides to hire a prostitute, a young woman named Chloe who she has seen in the Yorkville neighborhood of her office. Chloe's one time only job for Catherine is to encounter David at one of his regular haunts pretending to be a student, flirt with him to see what his reaction is, and report back to Catherine. Chloe is not to take it any further, meaning no touching let alone no sex. But this one time only job gets extended for various reasons. Chloe's job takes on unexpected dimensions, both for her and for Catherine and not only affects the two of them but also David, Michael and Catherine's practice.
Balancing family with a successful career, Catherine Stewart, a gynaecologist, after years of being happily married to David, a college professor, starts to believe that the reason for her stagnant marriage is her husband's infidelity, a suspicion fuelled after finding a compromising photo of him with one of his students on his cellphone. Insecure but curious to find out whether David is prone to adultery, Catherine, while looking down from the window in her office, she will spot Chloe, a young and elegant escort girl and she will hire her as a honey trap to flirt, seduce and report back. Without a doubt, Chloe is intelligent and quite proficient in her job, so before long, Catherine will be the recipient of the explicitly vivid descriptions of their passionate encounters that will ignite an unprecedented and inexplicable urge to hear more. However, as the appointments multiply, Catherine inadvertently, she will lose control while putting her entire family at risk..
A doctor hires an escort to seduce her husband, whom she suspects of cheating, though unforeseen events put the marriage in danger.
- Chloe (Amanda Seyfried) is a young woman who is discussing her business as a call girl to the viewers. She explains that she must be capable of pleasing her clients with her words, as well as with her actions.
Catherine (Julianne Moore), a middle-aged gynecologist living in Toronto, is working in her office. She glances out of her window at different times to see Chloe entering the hotel down the street from her office with her clients. Catherine's husband David (Liam Neeson), a college professor, lectures to a class in New York. At the end of the lecture, an attractive female student says that some of the class wants to take him to dinner. He politely declines, saying it is his birthday and he is supposed to return home. The whole class begins to sing 'Happy Birthday to You.'
Catherine hosts a surprise birthday party for David, who has not yet arrived. Assuring the guests that David is just minutes away, she gets a call from him saying that he missed his flight and will not make it home in time for his birthday. While David is on the phone, one of his female students is shown to be at his side.
The next morning, Catherine wakes up to find David at home. He apologizes to her, saying that he didn't know there was a party for him. Though it is an hour before David normally leaves for work, he tells Catherine he that must leave early so he can get coffee. Catherine finds her 17-year-old son Michael (Max Thieriot) with his girlfriend, who is walking around the house in her underwear. Disturbed, Catherine asks if they're using protection. Michael says that David knows about his girlfriend spending the night. The relationship between Catherine and Michael seems strained. Catherine suspects David of having an affair after she sees a picture of him and the female student hugging as part of a text message saying, "Thanks for last night" (the night of David's birthday when he said he missed his flight).
That evening, David and Catherine go out to dinner with two friends. David flirts with the waitress, clearly upsetting Catherine. Catherine goes to the restroom and enters a stall. Overhearing a woman crying in the next stall, she asks her if everything is okay. The woman replies evasively, saying that there is no toilet paper. Catherine hands her some under the partition. The woman states that "men are such assholes." Catherine agrees, then exits her stall. The woman (Chloe) follows her.
As they are washing their hands, Chloe offers Catherine her hairpin. Catherine kindly refuses, then says she must return to her husband. During dinner, Catherine notices Chloe, still upset, with another client at a table a short distance away.
The next day after work, Catherine stops by the hotel bar where Chloe spends the majority of her time waiting for potential clients. Chloe, looking at Catherine passionately, tells her that she "doesn't usually meet with women." Catherine reassures Chloe, explaining that she suspects her husband of infidelity. She wants Chloe to go to David's coffee shop in the morning and meet with him in order to test his loyalty.
The next morning, Chloe goes to the coffee shop and waits where David shows up as expected. Chloe hesitates, and then goes over to him to ask if she could borrow some sugar from his table for the container at hers is empty. David makes eye contact with Chloe and gives her the sugar dispenser.
Later that afternoon, Catherine and Chloe meet. Chloe describes the meeting with David, saying he was friendly, but only mildly flirtatious and that nothing really happened. Curious, Catherine asks Chloe how she does what she does. Chloe speaks openly about herself, how she tries to see good in people, and that all sorts of folks walk into her life-- including Catherine herself. Catherine pays Chloe and asks she meet with David one more time to see what he does.
That evening Catherine sees David speaking with someone via instant-message and chuckling lightly. Passing by Michael's room, she overhears him talking to his girlfriend on video-conference. She is trying to put some distance between them, supposedly because of upcoming graduation, but Michael thinks there are other reasons. Suddenly he sees his girlfriend staring over his shoulder. Turning, he angrily springs to his feet and closes the door in Catherine's face.
Catherine goes back downstairs and tells David that Michael's girlfriend is leaving him. She suspects she's responsible because of her disapproval that the girl was sleeping over with Michael. David assures her that Michael will be okay. He shares a sip of the Scotch that Catherine bought for his birthday, with her and they start to reconnect, wondering when they stopped being the young lovers that always picked each other up at the airport and couldn't stand to be apart.
The next morning, Catherine overhears Michael talking to David on his cell phone, comparing how he met his girlfriend, to how Catherine and David met-- a story Michael always liked to hear. Catherine smiles as she listens. Catherine's cell phone alerts her to a message from Chloe, asking Catherine to meet her at a restaurant.. Having been reassured about David, Catherine says she is feeling better about her relationship with him and doesn't need Chloe to see him anymore. But Chloe says she'd already met David again. Chloe starts to describe the encounter in more detail, disturbing Catherine. Chloe tells how she went with David to lunch, and then to a garden, where he kissed her passionately and she could feel him getting aroused. Catherine is deeply upset.
As Catherine tries to maneuver out of a tight parking space, Chloe gets on her bicycle to pedal away. Her bike skids and tips over on a patch of snow, and Chloe skins her knee. Catherine takes Chloe back inside and opens her medical bag to bandage up Chloe's knee. As she starts to take a medical scissors to cut Chloe's pantyhose away from her knee, Chloe declines and slides them down, which disquiets Catherine.
Later, Chloe is describing the meeting with David further, in more detail. She tells how she kissed David in a hidden niche in the gardens and gave him a hand job. Catherine awkwardly asks for reassurance that Chloe is 'clean' of any STD's, and Chloe promises to bring her medical documents showing this.
Catherine drives home and showers. As she washes herself, her mind spins with images drawn from the stories Chloe told her about her meeting with David. As Catherine lies down to sleep, David is seen awake in the bed beside her; his face pinched with anxiety.
Chloe goes to Catherine's office the next day to bring in her medical documents. She overhears Michael telling the receptionist that he needs to pick up his tuxedo for a recital. Chloe approaches Michael as he is photocopying musical sheets and talks to him about her favorite band.
Chloe gives Catherine the papers and tells her that she is meeting David again as per Catherine's request, later that day. Michael gives Catherine a much cooler reception as he picks his tuxedo up, not even thanking her as he walks out.
Lunching with friends, Catherine receives a text message from Chloe, asking her to meet her at a hotel. When Catherine arrives at the hotel room, the bathrobe-clad Chloe tells her that she had sex with David. She describes the encounter in explicit detail, but rather than causing Catherine more heartbreak, it arouses her. Chloe, feeling remorse, kisses Catherine, who abruptly leaves shocked by this sudden display of affection.
That evening, Catherine goes the music recital where Michael is playing the piano on stage to an audience. She sits a distance away from David, which is not lost on either him or Michael. Driven somewhat crazy by the haunting music and by both David and Michael's responses at ignoring her, Catherine leaves before the recital is over.
The upset Catherine meets Chloe at the hotel where Catherine asks her to describe more about her encounters with David. Chloe takes her up to a room and after sensually describing her moves, she has sex with Catherine. Afterwards, Catherine and Chloe share a taxi, with Catherine paying for Chloe's trip home. As Catherine gets out of the taxi, Chloe offers her her hairpin again. Chloe says that the hairpin was her mother's, and she now wants Catherine to have it as a symbol of her love for her. Catherine doesn't reply to Chloe or take the hairpin.
Catherine enters her home to find David waiting for her. He asks her if she's been unfaithful. Catherine becomes infuriated and tells him she's been meaning to ask him the same question. David declines to respond.
The next afternoon, Catherine arrives at her office after lunch to find several missed calls from Chloe and an e-mail with a picture of them in bed together at the hotel from that night. Alarmed, Catherine calls her. Chloe tells Catherine that she is waiting in her waiting room. Chloe suddenly enters Catherine's office seconds later with flowers, and asks her if she enjoyed the sex with her the night before. Embarrassed, Catherine admits that she did, but explains that their business is finished. Heartbroken, Chloe tells Catherine that she loves her. Catherine, disturbed, apologizes to Chloe for mis-communicating. She thanks Chloe for helping her, and pays her for the work she has done. Chloe leaves Catherine's office crying.
Seeking revenge, Chloe goes to Michael's hockey practice. They flirt a bit with Chloe bringing up intimate pieces of information regarding his FaceBook profile, especially a picture of him and his mother. She then gives him a 'Raised By Swans' CD at which point he admits he has already downloaded all of their music.
That night, Catherine and David go to a coffee house, where Catherine demands that David admit that he is having an affair. David admits that he did lie to her that night about missing his flight home because he hated to go to the birthday party, but he denies that he is having an affair. Chloe suddenly walks in, shocking Catherine. David looks around to see at whom Catherine is staring. He apparently does not know Chloe when, in a genuine baffled tone, he asks who the girl is, and why Catherine is so upset. At this point, Catherine realizes that Chloe made up her encounters with David to come between Catherine and David. Catherine also realizes that Chloe has apparently fallen in love with her because Catherine gave her attention.
Catherine apologizes to David for not having trusted him, and admits that she worried about him because she was getting older and more insecure about her appearance. Then she confesses her sexual encounters with Chloe. David, shocked but understanding, embraces and kisses her.
Jealous, Chloe goes to Catherine's home. Catherine arrives to find Chloe and Michael in Catherine's bed having sex. After sending Michael out of the room, the angry Chloe accuses Catherine of thinking that she could invite someone into her life, use them, then order them away when she's finished... just like all of her other male clients. Chloe tells Catherine that "money isn't enough to make her go away". Chloe wields her hairpin haphazardly, pricking her own hand and causing it to bleed, then pushing it up against Catherin's neck like a knife. Catherine apologizes fearfully and asks Chloe what she wants. She replies, "I want you to kiss me." Catherine kisses Chloe as Michael sneaks back into the room. Upon seeing Michael's reflection in the window, Catherine is surprised and pushes Chloe away. Chloe falls against a large window which breaks. The camera closes in on Catherine, then Chloe, as Catherine watches Chloe slowly letting go of the window frame and subsequently falling through the bedroom window to her death on the patio below.
Several months later, at Michael's high school graduation party, Catherine obviously is still upset by Chloe's death. One of the guests comes up behind Catherine to talk; as Catherine turns, she is seen to be wearing Chloe's hairpin in her hair.