Not much is revealed about Heather's backstory, only that she had been home-schooled by Claire after she was bullied at her school. One day, Heather arrived home and saw a woman that had beaten to death by her mother, who then revealed her victim as Jessica Fenton, Dwight's mistress. Heather went along with the rest of her family in covering up Jessica's murder, which was done by burying Jessica at Red Rock Canyon and later inviting transient Doug Adamson to stay at the home, doing so as part of Dwight's plan to fake their deaths and set Adamson up as their killer.
Heather also saw Ethan and Dwight drop off the former's car, only to later see Ethan coming out and covered in blood, realizing that he killed their father. After discovering Dwight's body, CSI went on the search for the rest of the family and learned that Claire used Jessica's credit card to buy three bus passes, while also hiding out at a motel. Once they arrived, they found Heather all by herself, and she was later interrogated by Jim Brass. During her interrogation, Heather revealed everything that happened, while also voicing anger over her family "making decisions in her life." The villainess also revealed Ethan's role in their father's murder, and blamed everything that happened on Dwight's affair, as well as accusing her family of ruining her life.
When Brass asked Heather about the whereabouts of her mother and brother, she stated on several occasions that she had no idea where they were. Brass dismissed her claim, which led to Heather responding that Ethan and Claire went to a movie and she hadn't seen them since. The final shot of the episode showed Claire and Ethan both dead and buried at Red Rock Canyon, subtly indicating that Heather had grown enraged at her mother and brother and killed them. The episode ended without revealing Heather's fate.