Spoiler alert! Please do not read the following plot summary if you have not seen the film.PLOT SUMMARY
Claire Peterson is a local high school teacher who specializes in Classical Literature. Living separated from her husband Garett, who was sleeping with his secretary and cheating on her, she is raising her son Kevin alone. Though Claire wants to work out her marriage despite the rough times, her best friend Vicky advises her against it and pesters her to file a divorce. Claire's son is ailing from an unusual allergy and on her way out for one of their trip to the doctor's (that her son does his best to resist), she meets Noah. He is the orphaned grand-nephew of her ailing neighbour, who is soon to undergo a bone marrow transplant. In no time, Noah and Kevin become friends and as a result Noah becomes a regular fixture in Claire's home. Claire and Noah begin to bond over their love for classical literature. She mentions to him that she will be teaching her class Homer that semester and Noah expresses his love for Illiad and Odyssey, winning her liking instantly.
Garett and Kevin take a weekend trip away which Claire refuses to go for as she still suspects Garett is sleeping with his secretary. Claire, while going to bed, spots an undressed Noah through her window and spends time looking at him through the drapes and vice-versa.
Claire's bff Vicky and her boyfriend Ethan take her on a double-date where the guy turns out to be a douche. Cooper and Claire have a face-off of kinds and Claire leaves the restaurant mid-way through her meal. Gulping down glasses of wine back home, foffended by her bad date, Claire gets a call from Noah to help him defrost chicken. Claire rushes to his place where alcohol and loneliness get the better of her and she succumbs to Noah's luring and seduction. The two engage in a steamy love-making session only for her to wake up in guilt next morning. Noah makes breakfast for Claire and she tells him that she regrets what she did. In a fit of anger Noah punches the wall.
School year begins on a fearful note as Claire realizes that Noah hacked her email to sign up for her class that season. Noah begins his malicious game with poisoning Kevin against his father as Claire and Garett do their best to med differences.Kevin gives up his usual class for boxing due to Noah's influence and after a stint of over-exertion, Kevin gets an attack in gym and Noah saves him.
Claire gets flowers at work and she expects they are from her husband only to realize it was Noah's doing. She confronts him and requests that they begin afresh.
Noah, trying to avenge a bully who was bothering Kevin, repeatedly bangs the boy's head in teh locker. When brought to Vicky who mentions how he was thrown out of his last school for disorderly conduct, Noah throws around chairs in her office and she expels him.
Kevin takes his long-time crush for the school dance and on the same night when Claire goes to check a leak in boy's bathroom, she finds 'I fu***d Claire Peterson' written in bold over the mirror. Noah attempts to force himself on her and Claire averts him and makes it clear that such things won't scare her and that he must stay away from Kevin.
The next day Noah leaves Claire's classroom filled with pictures of his and her lovemaking. It turns out that he had filmed it and has a video that can be used against Claire.
Garett offers to take Kevin on a drive and Kevin in rage over speeds the car, its brakes fail and the two almost miss a major accident by a blink.
Claire goes to Vicky for help and the two structure a plan together where Claire could sneak into Noah's house and destroy the video. Claire manages to get the video but she realizes a bigger secret that Noah was responsible for the car-accident of his father. he had tampered with the brakes of the car just like he did with Garett's car.
Noah attacks Vicky first. He gags Vicky and uses her voice to get Claire to come to her place. Noah kills Vicky and she comes home to find Vicky's dead body. Noah also kidnaps Garett and Kevin in a barn close-by. After a violent sequence, Claire kills Noah and saves her family. Garett is shot by Noah and the last scene wraps with she and Kevin taking him to the hospital.
