Audiobook Review: The Unknown by Riley Sager

I received a review copy from the publisher. This does not affect the contents of my review and all opinions are my own.

The Unknown by Riley Sager

Mogsy’s Rating (Overall): 3.5 of 5 stars

Genre: Horror, Thriller, Mystery

Series: Stand Alone

Publisher: Penguin Audio (August 4, 2026)

Length: 11 hrs and 33 mins

Author Information: Website | Twitter

Narrators: Maggie Grace, Patricia Santomasso, Erin Lin, Riley Sager

I make a point of reading Riley Sager’s new releases every year, even though my experiences with his books have been somewhat hit or miss. Not every book has worked for me, but I keep coming back because they’re entertaining, even (or especially) if they tend to be over the top. The Unknown certainly had a premise that fit that bill. It wasn’t without its flaws, but it turned out to be great fun.

In 1926, five women vanished under mysterious circumstances on a remote island in Vermont. Now, a century later, a small film crew is returning to the scene to recreate the events surrounding their disappearance. Our protagonist is Marin Keane, a struggling actress whose major credits thus far consist of one rather embarrassing commercial for eczema cream. But a career-changing opportunity unexpectedly lands in her lap when she’s tapped to replace another actress in a major motion picture. Suddenly, Marin finds herself starring alongside a legendary Academy Award-winning actress and an up-and-coming director. Their film is based on the notorious case of a group of spiritual mediums who went missing after retreating to the secluded island of New Avalon, leaving behind nothing but their dresses hanging from the branches of an old oak tree.

It’s the role of a lifetime and Marin’s chance to finally make a name for herself. But there’s a catch. The director is a firm believer in extreme immersion acting, and he and his team insist that the cast fully immerse themselves in the lives of the women they’re portraying. That means spending the production time living as they supposedly did, under rustic conditions with no running water, no electricity, and absolutely no cell phones. What no one anticipates, however, is an emergency that leaves the entire group stranded on the island. Cut off from the outside world and with no one coming to their rescue, the cast soon find themselves dealing with strange occurrences that bear an unsettling resemblance to the original events that unfolded a hundred years ago. Marin begins to question whether there’s a perfectly rational explanation for what’s happening, or if it’s the island’s supernatural reputation might actually have some truth to it after all.

One of the things I enjoyed most about The Unknown was its setup. While it’s ridiculous that no one seemed to question the wisdom of sending pampered actresses off to rough it in the wilderness in the name of making a movie about a real-life tragedy more authentic, I did love the premise. And sure, the plot is stacked with clichés, but they happen to be some of my favorites, including isolated locations involving groups of trapped outsiders. New Avalon makes for a particularly creepy setting, with its old legends, ominous trees, and strange markings. Think Blair Witch Project vibes. Overall, the book had an almost gothic, kind of old-fashioned haunted island quality to it. Whether it’s ghosts, a curse, or something much more ordinary causing all the trouble, there’s always enough uncertainty to keep the mystery going.

There’s also a two-timeline structure. Present day events run alongside another thread, which is taken from a diary written by a girl named Daisy, one of the missing victims from 1926. In this way, Sager fills in New Avalon’s history without too much boring exposition while allowing the two stories to develop together. Part of the book’s appeal was comparing the past and present and trying to piece together which details are significant and which might be red herrings. That said, I also wish the diary had offered more insight into Daisy as a character, rather than having her serve primarily as a plot device.

In terms of other criticisms, I had some issues with the story’s execution, as well as some doubts related to the characters themselves. Marin and her costars don’t often make the most sensible decisions, and in fact, one can argue that, from the start, this whole exercise in character immersion is an exercise in poor judgment. The circumstances which led to the group being stranded required a fair amount of suspension of disbelief. I can usually go along with it, but there were moments when the plot felt a little contrived, with some of the character dynamics and romantic developments feeling forced. Without getting spoilery, I also found it hard to buy into the ending, which wrapped up too neatly and glossed over heavier themes like sexual exploitation, abuse of authority, and mental health.

Still, at the end of the day, I was entertained. The audiobook also made for an enjoyable listen, with solid narration that made the story fly by. Overall, I’m glad I read The Unknown despite its flaws. Besides, sometimes just going along with it is part of the fun of reading a Riley Sager book. He certainly knows how to put together an easy-to-read thriller, questionable plot developments be damned.