Vanessa Lutz, portrayed by Reese Witherspoon, is a resilient 14-year-old girl trying to survive in a rough Los Angeles neighborhood. Living in a decrepit motel with her neglectful mother, Ramona (Amanda Plummer), who battles drug addiction and engages in prostitution to make ends meet, Vanessa's life is fraught with turmoil. The situation worsens when her mother’s boyfriend, Larry (Michael T. Weiss), not only gets high but also sexually abuses her. Things take a turn when the police arrest both Ramona and Larry during a sting operation, leaving Vanessa to face a life in foster care—a fate she desperately wants to escape.
In a moment of desperation, Vanessa handcuffs her social worker to a bed and steals her car, making her way out of the city after saying goodbye to her boyfriend, Chopper (Bokeem Woodbine). He hands her a gun, advising her to pawn it for cash. Tragically, moments after she leaves, Chopper becomes a target and is fatally shot.
Vanessa's journey takes a sinister turn when her stolen car breaks down on the I-5 freeway, where she encounters Bob Wolverton (Kiefer Sutherland). Initially appearing kind and helpful, Bob gives her a ride and persuades her to share her troubled past. Over dinner, he feigns interest in a therapeutic conversation, but reveals his true nature as the infamous "I-5 Killer," who preys on young women. In a gripping moment of realization, she confronts him, saying, > "You act like you're on some kind of mission, but you really just wanna get off in a sex type way."
With courage beyond her years, Vanessa uses her intelligence to turn the tables on Bob. After retrieving Chopper’s gun from the backseat, she forces him off the freeway and confronts him about his heinous actions. In an emotional climax, Vanessa shoots Bob, grappling with the horror of her actions as she empties the gun and walks into a diner, covered in blood, where police soon apprehend her.
At the police station, she confidently recounts her story—despite their disbelief, the officers only see her lengthy criminal record to discredit her. During her arraignment, she maintains that Bob is indeed the I-5 Killer and takes twisted satisfaction witnessing his injuries.
In the juvenile detention center, Vanessa faces challenges as she navigates new relationships with other inmates, including a troubled girl named Rhonda (Brittany Murphy) and a fierce Latina named Mesquita (Alanna Ubach). Amidst the chaos, Vanessa plots her escape, ultimately leading to a violent confrontation that leaves guards and inmates shaken.
As Bob and his wife, Mimi (Brooke Shields), appear to maintain their façade, the investigation begins to unearth the truth about his dark past. Eventually, a detective starts to believe Vanessa’s claims after finding compelling evidence connecting Bob to his crimes, all while the media label him a victim.
In a desperate act of survival, Vanessa uses her newfound skills to disguise herself and rob a man, propelling her toward the home of her estranged grandmother. But fate has a chilling twist; upon arrival, she discovers Bob has already murdered her grandmother and assuming her identity.
In a fierce struggle, Vanessa ultimately kills Bob and, upon surrendering to the arriving detectives, finds an unexpected moment of connection with them. In an exhausted, emotionally charged exchange, they all share a laugh, leaving Vanessa with a sense of bittersweet resolution in a world filled with chaos.
