Book Review - The Unknown by Riley Sager

Title: The Unknown
Author: Riley Sager
Genre: Thriller/ Horror
Published: 2026
 
Description: 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 on 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.
 
Review: Riley Sager is back with his latest thriller “The Unknown”, and it makes for a very entertaining read. In my opinion, this is a big improvement over his last two books, which unfortunately fell short. His 2025 release “With a Vengeance” I didn’t even finish. Although it’s not a new favorite, Sager does prove with this book that he still has a knack for the suspenseful thriller genre.
 
We meet Marin, a struggling actress who unexpectedly lands a major role in a movie directed by a popular director. The movie centers around a century-old mystery. In 1926 five women mysteriously vanished from New Avalon, a remote commune in Lake Faraday. To prepare for the film, the director gathers the cast on this island for an immersive rehearsal week. However, as the cast dives into the history and begins reading the diary of one of the missing women, the line between fiction and reality start to blur. And history seems to repeat itself.
 
The atmosphere here is the best part: Gothic and deeply unsettling. The dual-timeline between the commune of 1926 and the modern-day indie film set is highly compelling. The isolated island setting immediately ramps up the tension and the concept of actor being trapped there gives it a psychological touch. The book has supernatural elements, that you will question the entire time.
 
Riley Sager is known for his plot twists and he succeeds for the most part in “The Unknown”. It’s surprising and it takes some dark and twisty turns, but the conclusion eventually feels a bit far-fetched. It requires a heavy suspension of disbelief. If you don’t think it through too much it’s pretty good, but there are a few plot holes that don’t make sense. I do love how Sager made you guessing whether certain things really happened or not, right until the very end.
 
Sager is back, I liked “The Unknown “ so much better than the two book that came before this. But it does not match “The Only One Left” or “Lock Every Door”.
 
Rating: 3, 5/ 5