The Unknown (Pre-Order Aug. 4, 2026)

The Unknown by Riley Sager (Pre-order Aug. 4, 2026)

A chilling psychological thriller where a century-old disappearance, a haunted island, and a film crew trapped by dark secrets collide in Riley Sager's most suspenseful mystery yet.

One island. Two generations of disappearances. One terrifying mystery waiting to be uncovered.

From New York Times bestselling author Riley Sager comes The Unknown, an atmospheric thriller that blends psychological suspense, supernatural mystery, and gothic horror into an unforgettable page-turner.

Aspiring actress Marin Keane finally catches her big break when she's cast in a major Hollywood film based on one of America's most haunting unsolved mysteries—the disappearance of five women from New Avalon, a secluded island on Lake Faraday, Vermont, in 1926.

Before filming begins, the cast travels to the island for a week of research.

But New Avalon has a dark history.

Once home to a commune of spiritual mediums, the island became infamous after five women mysteriously vanished without a trace. The only evidence left behind was five empty dresses hanging from the branches of an ancient oak tree. Some believe the women were murdered. Others insist they fled. But the most chilling theory comes from the diary of Daisy Rue, one of the missing women, who claimed a séance unleashed something ancient and terrifying.

Soon after arriving, Marin and her fellow cast members—including legendary actress Violet Wright and acclaimed director Ronan Peters—begin experiencing unsettling events. Strange symbols appear throughout the island, eerie sounds echo through the woods, and an unexpected emergency leaves everyone stranded with no way off.

Then people begin disappearing.

As fear, paranoia, and suspicion consume the group, Marin turns to Daisy's century-old journal, determined to uncover the truth before New Avalon's horrifying past claims new victims.

Packed with gothic atmosphere, shocking twists, isolated suspense, and Riley Sager's signature storytelling, The Unknown is a haunting thriller that keeps readers guessing until the final page.

Why readers love The Unknown:

🏝️ Isolated island setting with eerie gothic atmosphere

👻 Supernatural mystery mixed with psychological suspense

🎬 Hollywood film crew trapped in a century-old disappearance

🔎 Twisty investigation with shocking revelations and unforgettable suspense

Perfect for fans of:

The Only One Left, The House Across the Lake, Mexican Gothic, The Silent Patient, and readers who love gothic thrillers, haunted locations, locked-room mysteries, and supernatural suspense.

🔍 SEO Keywords:

The Unknown Riley Sager, Riley Sager new book, psychological thriller, gothic mystery, supernatural thriller, haunted island novel, Vermont mystery, disappearance thriller, suspense novel, horror mystery