The theme that drives the plot of the novel the most is that of lies and secrets, as Julia is intent on uncovering any truths about the sister she hardly knew. Finding Olga’s hidden belongings sets Julia off on a quest to uncover what else her seemingly perfect sister may have been hiding, and along the way, she discovers even more painful secrets about her parents. 

When Julia learns of Olga’s years-long affair with Dr. Castillo—and even more troubling, that she was pregnant with his child—the revelation does not make Julia feel as vindicated as she had hoped. Her suspicions are validated, and she finally has confirmation that Olga was not nearly as perfect as everyone thought she was, but Julia cannot help but feel sorry for Olga, knowing that her sister put her entire life on hold for a delusional fantasy. Julia desperately wants to share this with her parents, in part because she resents being the only daughter constantly scrutinized, but also because she genuinely believes her parents deserve the truth. Ultimately, she cannot bring herself to tell Amá and Apa, because she knows their pain is not worth the satisfaction or relief it might bring her.  

She carries the knowledge of Olga’s affair with her to Mexico, where Tia Fermina, Amá’s sister, cannot help but tell Julia of Amá’s traumatic border crossing.