In Slaughter’s new standalone thriller, Pretty Girls, two siblings must cope with the loss of their older sister.

Whenever I start a new book, I remind myself that I am writing about crimes that happen to people every day—sometimes, in the case of sexual assault, every few minutes. While I usually tell the story from the perspective of the investigators trying to find the perpetrator, I have never really focused an entire work on the families of the victims. With Pretty Girls, I saw the opportunity to talk not just about crime but what crime leaves behind.

Not many authors can tell you where ideas come from, but I’ve got the note card where I scribbled the Pretty Girls story line in the middle of the night. Usually when inspiration strikes late, the light of day reveals that I haven’t gotten an idea for a book so much as a psychiatric case study. But this time, I was clear about not just the plot but the characters who would tell the story. I knew that one of them would be a father who has lost a child, and I knew that the other two would be sisters.

As the youngest of three girls, most of my childhood works were revenge fantasies against my older sisters, so of course the sisters in Pretty Girls share some similarities to my own. Claire Carroll, like most youngest children, is smart and beautiful. Her middle sister, Lydia Carroll, like my own middle sister, has struggled in life, but managed to right herself. And then there is the oldest sister, Julia Carroll, who disappeared 24 years earlier—certainly not like my oldest sister, but if you tattle on me for breaking curfew, you should expect some literary payback even if it’s 35 years late.

Everyone has seminal moments in their lives. For Claire and Lydia, losing their sister was a tragedy that defined their lives. They both became unanchored from everything that had always made them feel safe: their family, their friends, their solidly middle-class lives. They were no longer the cheerleader or the girl who sang in a band. They were the girls whose sister went missing. The girls whose parents fell apart. The girls who were all alone. This one random crime against their sister completely changed not just who they were but who they were going to be.

To me, that’s the real story in Pretty Girls. As awful as crime can be, it’s what happens afterward—the struggling to get out of bed, to put one foot in front of the other, that alters people. We see this injustice writ large in Pretty Girls. For the Carrolls, losing Julia destroyed their family. Not knowing why destroyed their lives.