Krystal Kellers is the daughter of Elise and Nathan Kellers, and before the film's events, she was in a relationship with Jack Davis, one of her father's employees. The couple dated for 9-10 months (according to Jack), and it came to an unhappy end due to Krystal's jealous and controlling behavior. As Jack revealed in the film, Krystal even planted a GPS in Jack's car.
Krystal moved on with a new boyfriend, Preston Durro, but that relationship mainly consisted of Krystal being obsessed with how Jack (in Krystal's twisted viewpoint) mistreated her. She even attempted to manipulate Preston into roughing up Jack for her, promising to pay him $30,000 to do so. When Preston refused, an angry Krystal paid a man to kill Preston, which he does when he runs into Preston while he was on his motorcycle.
Preston's death occurred in the film's opening scenes, and as the film progressed, Krystal's delusions increased immensely. Despite the fact that they were broken up at the time of the murder, Krystal continued to refer to Preston as her boyfriend, and later claimed that they were engaged during Preston's memorial service. To continue her delusions, Krystal broke into Preston's email account and deleted his emails that showed that he wasn't interested in her anymore; emails that were previously spotted by Preston's mother, Sandra, and his aunt, Carrie. Her obsessive anger towards Jack also increased, as after she failed to enter Jack's home, she actually killed one of his fish.
Later on, Krystal encountered Troy Krieger, one of Preston's friends, and engaged in a sexual encounter with him. After the tryst, Krystal overheard Sandra warning Troy about her over the phone, which prompted yet another evil scheme. The villainess later drove to Jack's home and attacked him with a knife and stabbing (non-fatally) him in the back. During her attack, Krystal stated that she had wanted to do this for a long time, accusing Jack of ruining her life. After leaving the house, Krystal drove home and noticed Sandra leaving the Kellers home after talking to Elise. She trailed Sandra in her car and later went after her with a gun in her possession.
During the confrontation, Krystal brashly confessed to killing Preston, stating that he didn't love her as much as she loved him. Her attempt to kill Sandra was stopped when Nathan drove up and confronted his daughter over her actions, and later called the police on Krystal. Krystal verbally lashed out at her father, right before she shot and killed him.
A year later, a private hearing was held for Krystal, who was charged for two murders (Preston and her father), as well as the attempted murder of Jack, who attended the hearing. It was revealed that Krystal was planning to set up Troy for the attack on Jack, and she was later sentenced to life in prison.
- Kate Mansi also appeared as main villainess Amy Thomas in the 2016 Lifetime film Unwanted Guest.