Rachel is barely coping with a lot of problems: a difficult divorce, moving her brother, being fired and raising a teenage son, Kyle. One morning, seriously late, the heroine gets into a traffic jam and starts honking at the driver, who refuses to go to the green light. When Rachel meets the man's gaze, he aggressively demands an apology. After she refuses, the man becomes enraged and begins threatening to kill her. But what Rachel doesn't realize yet is that she's made a ruthless enemy who will stop at nothing until she teaches the single mother a terrible lesson.