|“||I'm never gonna know, am I?||”|
— Yvonne in "Big Sea"
Yvonne's husband Paul died of unknown causes. Her daughter, Cindi, had a close relationship with her cousin, and Yvonne's nephew, Morgan. During their childhood, Morgan and his sisters, Sarah and Desiree, would spend time with Yvonne and Cindi when their mother went to work. In Cindi's adult years, she became endangered when a stalker, John Hitchens, set his eyes on her. At the time, the BAU had been called in to create a profile for the case, but things took a turn for the worse for Morgan when Cindi disappeared. The stalker killed himself two weeks after their arrival, and mysteriously, Cindi had yet to be found. Since then, whenever Yvonne hears of a case the BAU is investigating that raises the chance of Cindy being one of the victims, she would call Morgan for verification.
When the BAU is called in to investigate due to series of skeletons having been pumped out of the ocean while a Jacksonville beach undergoes cleaning, this prompts another call from Yvonne after she watches in the news Hotch giving up details of where this unsub would find and abduct his victims and asking for cooperation from families and friends of missing people in those areas. The call arrives at the same moment that Morgan learns that one of the skeletons found has been determined to belong to a woman who matches Cindi's overall physical description. Morgan tells her that they don't have much information about the victims yet. However, Yvonne is not convinced and travels to Jacksonville and visits Morgan just as the BAU is giving a profile on the unsub and offers him her daughter's hairbrush for DNA comparison, in answer to the plea made during the press conference.
When the unsub is captured, Morgan shows him pictures of missing persons, including a picture of Cindi. The unsub correctly guesses that Morgan has a personal connection with her and taunts him, saying that when he killed her she was shouting for her cousin to help her. Morgan instantly realizes he is lying because the unsub knew the names of each of his victims, but he didn't know Cindi's name. He returns to Yvonne and tells her the unsub has recognized Cindi as one of his victims but chooses not to tell her that he knows he's lying. Yvonne understands that it means her daughter is dead and hugs Morgan while crying in grief and relief for finding the closure she had been seeking all along.
Yvonne reappears after her niece Desiree spots a woman resembling Cindi before getting into a car accident. She visits Morgan, having been told by Sarah about Desiree's announcement, and slaps him in the face after he admits he lied to her. When it is revealed that John Hitchens was murdered and framed for being Cindi's stalker, Morgan gives her a photo of a suspect, Malcolm Ford, and she tells him that he was always at a church she and Cindi frequented.
It is soon revealed that Cindi is alive and being held captive by Malcolm Ford, but she had contracted a severe form of Stockholm syndrome, as demonstrated when she hires a lawyer for the apprehended Malcolm. Yvonne tries to appeal to Cindi, but she coldly turns her down, saying she has to "make dinner for him". It should be noted that she was referring to her son, Anthony, and not Malcolm. By the end of the episode, Cindi is rescued from Malcolm, and introduces her son to Yvonne. Yvonne happily embraces both of them.