Author Interview: Killing Sadie by Rachel Peterson

Everybody knows what happened at the barn party. Except nobody’s story quite matches. Killing Sadie is Rachel Peterson’s debut YA thriller, and it is the kind of book that keeps you second-guessing every narrator right up until the moment the whole thing snaps into focus. We got to talk to Rachel about writing unreliable voices, the characters she loved most, and what it actually takes to keep all those tiny contradictions straight. Check out her answers below and pick up Killing Sadie, just in time for summerween!

Killing Sadie

by Rachel Peterson
Published by: Simon Pulse
on August 4, 2026
Genres: Mystery, Young Adult
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Perfect for fans of How to Survive Your Murder and Dead Girls Can’t Tell Secrets, this young adult thriller unspools the truth behind a tragic murder through multiple unreliable narrators who all have secrets to keep.

Here’s what we do know: there was another infamous barn party at the McClain family farm last night, and things went horribly wrong. By the end of the night, there were two dead bodies in the old barn: seventeen-year-old Sadie Cooper and her killer, Mason Vreeland. The murder was heartbreakingly witnessed by Sadie’s twin sister, Jayne, and Sadie died in her arms. Mason was killed by Sadie’s boyfriend, Ben, in an attempt to save Sadie.

Aside from figuring out Mason’s motive, it should be an open and shut case.

But it’s not.

The story unfolds just after the murders, and Jayne, Ben, and Sadie’s best friend, Liz, are telling the cops what transpired at the party and the events leading up to it. But little details don’t match. And those little details start to add up to big discrepancies. But who’s lying, and why?

The shocking truth is revealed in the third act, when the POV shifts to victim Sadie herself, in the days leading up to the party. Witness exactly what happened—and see if you can piece it all together. Because poor Sadie totally missed what was right in front of her.

Interview with Rachel Peterson

This story unfolds through multiple perspectives with things not quite adding up. Was there a particular viewpoint that was the most fun or the trickiest to write, and why?

I love to let my characters surprise me, so while I have a general idea of the plot and action before jumping into writing sessions, certain viewpoints jump out at different times – which usually means I can be heard cackling and clapping my hands in front of the laptop when I hit an aha moment! My personal faves for Killing Sadie were the viewpoints of Sadie and Jayne, the Cooper twins. I think readers will resonate deeply with both characters at different points throughout the pages (team Sadie or team Jayne), because they really do represent so many aspects of the teenage experience. And the reader’s loyalty to any one character will no doubt change over time, which is such a fun part of any thriller!

The character of Ben was definitely the most fascinating to write. We’ve all met a Ben – the nice guy who reveals a dangerous side simmering just below the surface the moment things don’t go his way, leaving you shocked but not totally surprised. And the irony is, all Ben has to do is nothing – the status, the girlfriend and the lifestyle are his to lose – yet he completely unravels the deeper we go.

But the trickiest part of the whole writing experience? Keeping all the tiny details straight! As someone who has always struggled to color inside the proverbial lines, there were some amusing inconsistencies I totally missed that were caught by my wonderful copy editors. For example, the number of times one character already showered or still had to shower within a single scene … thanks for bearing with that one, early ARC readers!

The reveal shifts to Sadie’s own days before the party. If you could hang out with Sadie for one hour before everything changes, what do you imagine she would want to do most?

Amazing question! The obvious answer would be texting her bestie Liz nonstop about her barn party fit, pregaming hard and keeping 100% of her attention locked in on the various dramas unfolding within her relationship with Ben (which turns from hot to cold and back again faster than even she can keep track). If we were hanging out with Sadie an hour before the party, we might get the feeling that something sinister is brewing, but Sadie would be the last one to know that her perfectly architected world is about to fall apart … even though the clues were right in front of her the whole time!

Mystery stories often come from a real curiosity about what people don’t say. Was there a real-world moment or question that inspired you to play with unreliable narrators and hidden truths?

The idea of truth being both internal (what we tell ourselves) and external (what we tell each other) was a big inspiration for Killing Sadie, and something I was so curious to explore! There were a few major moments in my teenage years that seemed to impact every single person I knew, and it was interesting to see how one event could be interpreted in seemingly infinite ways, depending on each individual’s experience of it. That kind of ambiguity definitely comes through in our cast of unreliable narrators.

The big question is: Can a lie become the truth – whether to the person telling it, or the person hearing it – if delivered with enough conviction? When you couple that question with the teenage experience, which is so nuanced already, it really does make for unhinged twists and reveals! Killing Sadie takes a seemingly normal town (shoutout to my hometown in Ohio!) and seemingly normal teenagers, and pushes everyone to the edge with everything to lose. That’s when you discover that even the most unassuming characters can sharpen their knives!