The Unknown

by Riley Sager

The next twisty, tension-filled, dizzying thriller from the master of suspense. You'll never guess what's coming next.

ALL YOUR FAVOURITE AUTHORS ALREADY LOVE RILEY SAGER . . .
'Non-stop suspense with twists and turns that will leave your head spinning!' Freida McFadden
'Full of tension, urgency, atmosphere and feeling' Lee Child
'Propulsive . . . a dizzying Gothic whodunit' New York Times Book Review
'Riley Sager is an auto-buy for me' Laura Dave
'Riley Sager is one of my favourite authors . . . Fun, scary and so absorbing' Rachel Hawkins
'If you're not already reading Riley Sager, you're missing out' Catherine Ryan Howard
'Clever, twisty, spine-chilling' Ruth Ware
'Terrific' Karin Slaughter
'A dark, frightening and twisty story that you won't be able to put down' Shari Lapena
'The work of a master storyteller . . . An unputdownable page-turner' Alex Michaelides
'Brilliantly written with a dark and clever twist on a well-worn trope, and as for that ending...?!' Susi Holliday

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

368 pages, Hardcover

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

[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 🤧🤧

[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!!

[Laura Lovesreading]

I'm intrigued.... I think.... 💭💭💭

[Conny Godefroy]

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

[emma nicolette]

so seated for this one. sounds so good

[holli · Rating 3 out of 5]

3.5 ⭐️

riley sager is always an auto buy for me, and this premise had me hooked. the idea of 5 women disappearing without a trace off this island is nothing short of intriguing. i’m not usually a person who leans towards paranormal books, but this held my attention.

it was creepy, the descriptions made me feel uneasy and i definitely don’t recommend reading at nighttime. i was a little disappointed by the plot twist, but sager has a way of making you think you know what’s going on, when he rips the run out from under you. some of the writing felt a bit shallow and the point that is being made felt weak, but i enjoyed enjoyed myself. definitely pick this one up when it releases in august!

[Zach]

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

[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!

[Eric · Rating 4 out of 5]

The Unknown is peak Riley Sager catnip at the start: a century-old island mystery (five women vanish, dresses left hanging like a dare), a modern film crew heading to the exact location for “research,” and a diary that basically whispers you’re next. It’s got that glossy, cinematic vibe—stormy lake, creepy symbols, famous actors with egos, and the sense that the island is quietly watching everyone like an audience that wants blood.
And for a while? It’s legitimately fun. The setup snaps, the atmosphere is dialed in, and the “is this sabotage or supernatural?” question keeps the pages moving. Sager’s good at that momentum—he knows how to keep you leaning forward even when you’re side-eyeing the coincidences.
But then the reveal hit and I felt the air go out of the room. Not because it was messy, exactly—more because it didn’t feel inspired. The ingredients are so delicious that I wanted the payoff to be bolder, stranger, or more emotionally sharp. Instead, it landed in a place that felt safer than the premise deserved, like the book spent its best energy on the promise and then cashed it out for something more standard.

Still, the ride is entertaining. I just wanted the destination to match the mood.

[Jessica · Rating 3 out of 5]

(Thanks to Netgalley for an ARC)

A mysterious island off the coast of Vermont, steeped in unsolved disappearances, finds itself at the center of an indie horror film 100 years after its sinister events took place.

Well, I wish that the initial three fourths of this novel were as entertaining and twisty as the last one! Truly, I would have given this book a measly 2 stars had it not been for the last 75 or so pages that saved it. The initial pacing was just off. I found the Daisy journal entries flat out boring and the present-day/Marin chapters slow and predictable. It wasn't until the twists were revealed that everything started to gain momentum. Most of the time this read like a rehashing of The Lost Village and Run Time, so really I just kept reading it thinking "this has all been done before". Unfortunately, that seems to be a recurring thought of mine with Sager's more recent novels. But the last fourth of this gave me that old Sager flair that I have so desperately missed. So three out of five stars for breathing some originality back into the conclusion. I enjoyed the Me Too messages and think Sager did a great job with the portrayal of that issue!

[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.

[Robin · Rating 5 out of 5]

This is Riley Sager's best book yet! It is quite a winner! On an island in Vermont 100 years ago 5 women disappeared. Now, a film crew is "rehearsing" the movie on that same island, hoping to find realism and truth. Instead, the women begin to disappear, following the diary left behind by one of the women in 1926. There are seances and scares and disappearances and sounds and bumps in the night. Chapters rotate between the 1926 diary entries and 2026 activities. The diary is missing pages at the end, so the movie script continues the story on its own. I am amazed at the depth of plot and the intricacy of the characters. So much is going on here and it is so well-written that I could not stop! I wish I could give it 10 stars!!! My only concern is how will Mr. Sager ever top this book?! Thanks to NetGalley and Dutton for providing an ARC.

[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 🧐

[Chelsea]

This sounds exactly like the plot of "The Devil In Me"(Dark Pictures Anthology video game)??

[Owen]

**pre-order**

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