The Stepsister’s Secret

• Author: Karen King
• Genre: Mystery/Suspense
• Publication Date: February 16, 2026
• Publisher: Bookouture Audio

Thank you to NetGalley and Bookouture Audio for providing me with an ARC of this audiobook in exchange for an honest review.

She’s family now. But can I trust her?

When my stepsister Alison moves in to look after my mother, everyone in my family is grateful. Alison’s a nurse, and she says she just wants to help. But I don’t trust her.

Years ago, when Alison and I were the same age as my own son Isaac, I made a terrible mistake that tore Alison’s world apart. I hoped she didn’t realise, but the look in her icy blue eyes tells she knows exactly what I did.

I’m certain she’s responsible for my mother getting weaker. I don’t like the way she’s pushing me out, isolating me… and getting way too close to my husband, Nick.

I’m watching her. And I’ll do anything to keep my family safe. But I have no idea just how much danger we’re in…

A totally unputdownable, twisty story of family secrets that have deadly consequences. Perfect for fans of Shari Lapena, Freida McFadden, and Daniel Hurst.

Karen King is a new-to-me author, and I was looking forward to checking this one out. I wasn’t sure which way this would go for me, since it’s compared to books by Shari Lapena (love her writing) and Freida McFadden (not an author I read anymore since seeing her harmful and inaccurate mental health rep). I was hoping it would be as enjoyable as Lapena’s books are, even if it requires a little extra suspension of disbelief.

The story seemed pretty straightforward initially. Everyone seems to have secrets in this family, and I was thrilled about it. I love a suspense novel that is full of hidden secrets that are bound to come out at the worst possible time. There are multiple POV characters, including Alison, Lizzie, Nick, and Lizzie’s mother, and it seemed like a typical, predictable plot. 

However, it becomes clear that in addition to keeping huge secrets, not all of these narrators are reliable. Lizzie in particular becomes an unreliable narrator when more about her is revealed. I didn’t love that her mental health becomes a plot point along with her being unreliable, but it was presented relatively decently. She struggles with anxiety throughout the book as well, and she doesn’t always reach for the most helpful coping techniques. One of the techniques was to wear something around her wrist that she can snap when feeling anxious, which is a harm reduction technique commonly used to stop self-harm. However, she does so unconsciously to the point where it causes physical damage to her wrist. When her loved ones see her wearing it, they become more overprotective—viewing it as a sign that her anxiety levels as high and they assume that they need to ‘protect’ her rather than being actively supportive. I mean, I don’t think that it is an intentional response, but family doesn’t always know how to support a person with mental health issues.

Along with nearly everyone in the story walking on eggshells in an effort to manage Lizzie’s anxiety, Alison infantilizes Lizzie’s mother and everyone in the family simply views it as providing care to her stepmother (except for Lizzie). It becomes clear that Alison’s nursing skills are a way of controlling her new stepmother—she decides who can visit, how long they can stay, and what she is capable of handling, furthering the idea that Alison might be doing something to harm her. 

The audiobook is narrated by Imogen Church, who does a fantastic job of voicing multiple characters, tones, and even accents. It was a pleasure to listen to her, even if I wasn’t sure about the plot at first. Church makes the fast-paced chapters fly by, and it was an enjoyable experience. 

For the first part of the book, things seemed entirely too predictable. There’s a strange connection between Lizzie and Alison, dating back to when they were very young, around the same age as her 7-year-old son. It was a simple mistake with huge consequences, and it changed the course of the life of everyone involved in the story. This is where Lizzie’s crippling anxiety began, and it was surprising to me that no one in her family noticed the drastic change in her and questioned what it was about. But it’s easy for me to say that as a trained mental health counselor, while loved ones do their best with the limited information and supportive skills that they have. 

Initially, all of the evidence seem to point very clearly to Alison. Also, Alison doesn’t seem very mentally steady. She resorts to calling her new stepmother ‘Mum’ right away, and then cancels her return flight to Spain, offering to stay with her father and new mum so they can benefit from her training as a nurse. But something isn’t right—Lizzie’s mother has some worrying symptoms as she’s recovering from a fractured ankle. She’s tired all the time and has become especially weak, and has become completely dependent on Alison in the blink of an eye.

Overall, I found that I enjoyed the second half of the book a lot more than the first half. Whenever I read a mystery or suspense novel, I’ve learned that if everything points to one character, they’re usually the one person who isn’t involved at all. So I tried to stay open-minded, and really struggled with figuring out who the villain is. Most of the plot twists in the book were a complete surprise, so that every time I got to feeling like I knew what was going on, King would throw in a major twist that changed the entire direction of my thoughts. The plot twists were done so well, and each one altered the whole trajectory of the story along with my thoughts. Just be warned, this book is like popcorn—a little isn’t enough.

Bottom line: A compelling and enjoyable story, full of unpredictable twists and turns, high stakes, and lots of action to propel the story forward.

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