Tom Cooper, a mentally unstable man feeling powerless and invisible to the world, breaks into the home of his ex-wife and kills her and her boyfriend with a hammer, before setting the house on fire. He drives away as the house explodes.Rachel Flynn, a newly divorced single mother living in New Orleans, drives her 15-year-old son Kyle to school in rush hour traffic. She is running late to work and honks at a pickup truck failing to go through a green light. The owner of the truck, Tom, soon catches up to Rachel and apologizes, then asks for an apology in return. The exchange escalates when Rachel tells him that she has nothing to apologize for. A small chase ensues before Rachel loses Tom and is able to drop Kyle off.Tom tracks Rachel to a gas station and switches his phone with hers while she is inside the gas station. Rachel gets help from a customer who accompanies her back to her car and gets Tom's license plate number. Tom then rams the customer with his truck and aggressively pursues Rachel. When Rachel tries to contact her divorce lawyer Andy for help, she finds that Tom used the daily planner in her phone to locate Andy at a diner. Before she can warn Andy, Tom beats and stabs him to death.Tom continues to stalk Rachel. He goes to her brother Fred's house and kills his fiancée, Mary. Tom then ties Fred to a chair and tells Rachel that she has 3 minutes to go to the school, get Kyle and get as far away from the school as possible before he will set Fred on fire. She gets to the school, desperately demands that the principal releases Kyle. She gets him and drives away. Then, a police officer arrives at Rachel's house, where Tom is holding Fred captive. Tom sets Fred on fire and then the cop shoots Tom and tries to put the fire out as Tom escapes. After Rachel leaves with Kyle, Tom catches up with them on a highway. They use a tablet GPS application to locate her phone (and Tom, since Tom stole her phone earlier) and find out that her phone and Tom is in a minivan directly in front of them. When they attempt to alert a nearby police officer, Tom rams his cruiser, causing a massive multi-vehicle car accident.Tom pursues Rachel to her mother's house, where Kyle triggers a silent alarm and hides. Tom attacks Rachel in the driveway and seemingly knocks her out, then enters the house in search of Kyle. As he is about to walk back outside, Kyle inadvertently alerts Tom to his hiding place upstairs. Rachel enters the house in an attempt to protect Kyle, but Tom finds her and they struggle violently. When Tom begins to strangle Kyle, Rachel stabs Tom in the eye with scissors, killing him.The police arrive and inform Rachel that Fred survived the attack. Rachel and Kyle leave to see Fred at the hospital. As they drive away, a car cuts Rachel off, and she stops herself from honking at the angry driver. Kyle observes and notes, "Good choice."---from Wikipedia, Text is available under the Creative Commons Attribution-ShareAlike License.