The Unknown

by Riley Sager

12 hours

In 1926, five women disappeared from a remote island in Vermont. Now, one hundred years later, it’s happening again.

Struggling actress Marin Keane is shocked when she lands a role in a major motion picture about the unsolved mystery of New Avalon, an island on sprawling Lake Faraday in Vermont. She’s even more surprised when she learns that the role requires a weeklong research trip to that very spot.

Because New Avalon isn’t your ordinary island. A century ago, it was a commune for spiritual mediums—until they all vanished in 1926. The only trace of them was five dresses hanging from the branches of an old oak tree in the middle of the island, one for each missing woman. Some locals say they simply left. Others think they were murdered. But the prevailing opinion, thanks to a diary left behind by one of the vanished, a young woman named Daisy Rue, is that a séance gone wrong conjured something supernatural that took them all one by one.

Not long after arriving, Marin and her castmates, including legendary actress Violet Wright and white-hot director Ronan Peters, begin to realize all is not right with New Avalon. They hear strange noises in the night and notice mysterious symbols left behind by the island's previous occupants. And after a sudden health emergency leaves Marin, Ronan, and the other actors stranded on the island, the disappearances begin again.

Is it the work of someone trying to derail the movie? Or is the island’s alleged supernatural past catching up with the present? As fear and suspicion mount, Marin turns to Daisy’s diary, hoping it holds the key to figuring out what really happened to the women of New Avalon—and how to keep the island’s terrible history from repeating itself.

Genres: Mystery Thriller, Thriller, Mystery, Horror, Adult, Fiction, Paranormal

Audible Audio

Expected publication August 4, 2026

About the author

Riley Sager is the New York Times bestselling author of eight novels, most recently THE ONLY ONE LEFT and THE HOUSE ACROSS THE LAKE. His first thriller, FINAL GIRLS, won the ITW Thriller Award for Best Hardcover Novel and has been published in more than thirty-five countries. His latest novel, MIDDLE OF THE NIGHT, will be published in June.

A native of Pennsylvania, he now lives in Princeton, New Jersey. When he's not writing, he enjoys reading, cooking and going to the movies as much as possible. His favorite film is "Rear Window." Or maybe "Jaws." But probably, if he's being honest, "Mary Poppins."

Reviews

[Ghoul Von Horror]

How did no one tell me there was a new Riley Sager book coming out???

[Trisha]

For Riley Sager - I'm in!

But that synopsis sounds amazing! Can't wait for this one in 2026!! 🥳🎉🎊

*** UPDATE: That cover! OMG! I love it!!

[Conny Godefroy]

I don't care what everyone says, I'm seated for this.

[Laura Lovesreading]

I'm intrigued.... I think.... 💭💭💭

[emma nicolette]

so seated for this one. sounds so good

[Zach]

THAT COVER!!! This comes out the day before my birthday, soooo happy early birthday to me😩❤️

[shanayaa]

౨ৎ pre-read:
⤿ started - 26 January , 2026

ahhh, did I just get the ARC for my most anticipated read of the year??? YES OMGGGGG I’m crying 🤧🤧

[Madeline Church · Rating 4 out of 5]

One thing about Riley Sager novels is that each is going to have it's entirely own feel. It is the best thing about reading a book by him. Nowadays, each book by an author feels the same with only slight differences. The Unknown cannot really be compared to his other works, and that is the best compliment.

I am a supernatural media hater, usually. However, I actually really enjoyed the supernatural elements in this book. It was done so well, and I was never annoyed by it as I previously had been.

The premise is very interesting, and it will make you want to read from the first chapter. Five women disappearing from an island twice?? You want to know what is going to happen/leads up to the events. Getting both the present-day portion and the 1926 piece of the story was great. You were able to slowly piece parts together, and it broke up the repetitiveness a bit.

This book is not rated any higher because the first half did feel sort of slow. I was not completely engrossed in that portion as I would have wanted to be in a mystery thriller. It definitely picked up in the second half.

Thank you NetGalley, Dutton, & Riley Sager for an ARC in exchange for an honest review. The Unknown is released on August 4, 2026!

[Gina Malanga · Rating 5 out of 5]

This other, always kind of marketing themselves as a murder, mystery, author, but in the last couple books, a scene of movement towards the supernatural and the horror. This one is no different as a young unknown actress gets the potential job of a lifetime, but in order to do so she has to travel to an island where five women mysteriously disappeared to prep for the movie role she hopes will make her famous. But as things starts happening on the island. It’s impossible to deny that there seems to be some dark force at work here. I turned to the pages as quickly as possible and finished it in just a couple hours. It was a great read and definitely a little bit bit different for me in terms of the occult aspect. There are definitely some messages here about the power of men in Hollywood and how they treat women that made the boogie war impressive definitely one of my favorites by this author.

[Chelsea · Rating 3 out of 5]

Thanks to NetGalley for allowing me to read this in exchange for an honest review.

Sager’s last couple of books have been pretty meh. An unknown actress finds herself cast in what appears to be a huge movie with lots of big name actors attached. Why was she cast? And why do they need to be stranded on a mysterious island for a week before they start filming? The writing was good and there was a twist I didn’t see coming. But overall I was pretty disappointed. The majority of the book was a journal within the story that was basically just repeating the events that were happening in real time, so it was like reading the same story twice (up until the last quarter of the book). And I don’t care for twists that use mental illness as a plot device.

[Michelle · Rating 4 out of 5]

An eerie island setting, a century-old mystery, and a film crew cut off from the mainland—what could possibly go wrong? The story does a great job building tension as the cast and crew settle into New Avalon and quickly realize the island’s unsettling past isn’t done with them. The atmosphere is creepy and claustrophobic, with strange details and mounting suspicion that make every interaction feel loaded. The mix of paranoia, strange clues, and unanswered questions kept me guessing the whole time. As a big fan of Riley Sager, I wasn’t disappointed; this has the same addictive suspense and atmospheric twists that make his books so fun to read.

Many thanks to NetGalley and Dutton for providing an eARC prior to publication in exchange for an honest review.

[BHK · Rating 5 out of 5]

The Unknown by Riley Sager was soo good! The premise hooked me immediately…an eerie island, a century old mystery, and a modern film crew slowly realizing they’re in way over their heads. I loved the mix of old diary entries with the present day story. Daisy Rue’s perspective added such a creepy and haunting layer that made the past feel uncomfortably close. The island was isolated, unsettling, and full of secrets, with reveals coming just when I thought I had things figured out! If you like atmospheric thrillers with twists, moody settings, and a fast, bingeable vibe, this one is a must read!

[Laura]

the fact that this is tagged as fiction first should probably set my expectations.


and it probably wont 😂

[Kaleah]

Hmmm…I’m interested 🧐

[Owen]

**pre-order**

How the hell did I not know this was a thing till today!? Diabolical…