On the evening of October 28, 1995, a young Jamie Emerson attended Scare Fest, a Halloween-themed event at a local theme park, with her friend Johnny Ricketts. The pair rode the Ferris Wheel that night, but Jamie's latch belt wasn't properly locked. Because of this, both of them fell over, with Johnny falling to his death while attempting to save Jamie, who survived.
After the accident, park president David Wayland and vice president Frank Holloway forced park official Eve Asher to falsify the details of Johnny's death, while also paying off Johnny's family and Jamie--$350,000 each.
The park stopped doing Scare Fest until the episode's events, and when learning about Scare Fest returning, Jamie plotted a murderous revenge. She took a job at the park as a ride operator, doing so under the name Carol, and colluded with her boyfriend, Todd, in her plot. Carol was shown early in the episode running the Haunted House ride, while Todd was strangling Wayland to death, doing so dressed as Johnny. Shawn and Gus were on that ride, and when the latter tells Carol what he witnessed, she dismisses it as being part of the ride. Carol also dressed as Johnny in her plot, appearing to Holloway and to Eve in her disguise. She and Todd later killed Holloway at the log ride, leaving Eve as their final intended victim.
Shawn and Gus returned to the park after learning that Eve is next on the list, and it was there that Jamie's reveal occurred. Jamie vented her anger over Johnny's death, blaming the park and its officials, before wielding a knife and going after the trio. Gus knocks the knife out of Jamie's hands, but Shawn later figures out that she had help in her plan, which brought out Todd, who pointed a gun at the trio. The villainous couple later chased after the trio, and at that moment, Juliet appeared and knocked out Todd, while Lassie emerged with a handcuffed Jamie. The couple was arrested for the murders.