Earlier this week, Riley Sager released his newest book, The Unknown, so you know I immediately grabbed a copy for my Kindle. He’s one of the most recognized names in the horror/thriller crossover genre, and previously I’ve reviewed another work of his: Home Before Dark.

In 1926, on a small island in a lake in Vermont, 5 women mysteriously vanish, their dresses strung up in a giant tree that’s been split in half. The only clue remaining to their demise is the diary left behind by one of them, Daisy Rue, and her diary details a dark presence on the island that she believes to be demonic.

In 2026, a film is being made about their story, starring 4 well-established actresses and one newcomer, Marin Keane – our narrator. Marin and the other 4 are sent to the island for a week of in-depth method acting to warm them up before they start shooting on a set in North Carolina. They’re expected to live without electricity and dress in their characters’ wardrobes, only having access to food and commodities that would’ve been common a century ago on the island (along with their director, producer, and a crew member).

On the first night, they recreate the séance that was detailed in Daisy’s diary, and things go south pretty quick. The crew member has a medical emergency, so the producer grabs his bag and accompanies him back to the mainland… the same bag that had everyone’s cell phones inside. The actresses begin disappearing one by one, their dresses strung up in the very same tree. A sinister history repeats itself. The last few pages of Daisy’s diary have been lost to time, but Marin is about to find out what really happened on the island so long ago.

Firstly, I can tell you without a doubt that this is going to be one of the biggest releases for late summer/early autumn 2026. It’s eerie, it’s dark, it’s twisted and messed up (and will need a few content warnings for some heavy topics), and I had to keep reading it to find out what happened next – I literally finished this at 4 in the morning. Every time I thought I knew what was coming next, I was thrown in a direction I could’ve never predicted. This is the creepiest book I’ve read in a while, and frankly I loved it even more than Home Before Dark. The dual timeline of the present combined with Daisy’s diary was executed perfectly, and the attention to detail was incredible.

If you’re looking for the perfect atmospheric horror to finish off your summer reading, you really don’t want to miss this one. It’s impossible to put down. I read books every single day, but it’s been a while since one genuinely grasped my attention as much as this one did. I’m calling it now, BookTok is about to be all over this one – this is one of the best books of the year!