Ashley Carter's backstory revealed that she engaged in psychotic behavior as early as the age of six, as she murdered her mother when she didn't get her way. Since killing her mother, Ashley developed a twisted obsession of finding the "perfect mother" for her, which included befriending a girl named Courtney Lund.
Ashley and Courtney's friendship took a sinister turn due to Ashley's obsession and it led to the family filing a restraining order against her. Her stalking and persistence continued, and at one point, Ashley was actually arrested, but she made bail. Once she did, Ashley went to the home of Courtney and her mother, killing both of them in a psychotic rage, leaving Courtney's sister, April, to find the bodies.
In the film's events, Ashley introduced herself to main protagonist Summer Hughes, doing so under the name Cara Dawson and stating that she came from Hamilton and Jefferson high schools. She made a good impression on Summer, as well as Summer's mother Lianne, but her clingy behavior got on the nerves of Summer's best friend, Toni, who coerced Summer to throw a party with her at Summer's home and forget about Cara. Unbeknownst to the pair, Cara followed them and spotted their party, and she phoned the neighbors about it, resulting in Lianne grounding Summer.
By this time, Summer herself was bothered by Cara's obsession with her, to the point where she brushed off Cara and closed the door in her face, resulting in Cara going into a rage and throwing down the batch of cupcakes she baked. After a confrontation with Toni, Cara tracked Toni to Cara's home, where Toni found a plethora of photos of Summer. It was there that Cara killed Toni, and she later went after Lianne's co-worker/boyfriend, Steve, doing so under the belief that he was an obstacle in her quest to make Lianne her mother. After Toni's murder, Summer began to suspect Cara's true nature, leading her to head to Jefferson and talk to April about Cara/Ashley. April revealed what she and her family went though with the crazed villainess, but unbeknownst to them, the evil Cara tracked Summer to Jefferson, and after coming face to face with April, she bludgeoned her to death with a hammer. After killing April, Cara later knocked out Summer with a trophy, and took her to an abandoned home.
Cara tied up and gagged Summer, and she later revealed her true insane personality and her plans, stating that she would make a better daughter for Lianne due to Summer being "ungrateful." She later attacked Summer's boyfriend, Jason, when he attempted to save her, and was later called by Lianne regarding Summer's appearance. Cara later met Lianne, who she kept calling "Mom," and offered to help her find Summer, but became annoyed when Steve appeared to help out on the search. The group arrived at the house and found Summer and Jason, but it was at that moment that Cara attacked Steve and later faced Lianne. While brandishing a knife, Cara stated to Lianne that she could be her mother, while revealing that she killed her own for "making her angry." The psychotic villainess screamed at Lianne for not loving her, and it was at that moment that Summer arrived and plunged a knife into Cara.
When police arrived, however, Cara was not found, leaving just some of her blood at the scene. The end of the film saw Cara approaching another woman and her daughter, helping her with her groceries while telling the woman that she "looked like her mother," giving the indication that Cara had found her next victim.
- Cara Dawson is similar to Lifetime villainess Chloe Miller from 2017's Deadly Exchange; both are psychotic teenagers who befriend their respective film's teenage protagonist to get closer to their mother, who they are determined to make their new mother figure. Both women also sabotage and/or kill anyone who gets in the way of their deranged goal.