Some islands keep their secrets quietly. The one at the center of Riley Sager’s The Unknown keeps its by making sure nobody who learns them ever leaves to tell.
In 1926, five women vanished without a trace from a remote island off the Vermont coast, their disappearance folding into local legend and unanswered questions that never quite settled. A century later, a film crew — five actresses and their director — arrives on that same island to shoot a movie dramatizing the vanishing, only to discover the past isn’t nearly as finished with them as the history books suggest. Sager splits his narrative between the two timelines, letting the 1926 women’s own séances and unraveling trust mirror the modern crew’s slow realization that restaging a tragedy might be inviting a repeat of it.
What Sager does best here is atmosphere. The isolation of the island, the fog-bound estate, the sense that the water separating the cast from the mainland is also separating them from rescue — all of it is rendered with the patient, controlled dread that’s become his signature. The séance sequences, staged twice a century apart, are the book’s standout set pieces: unsettling less for jump-scares than for the dawning sense that something on the other side is answering back. The dual-timeline structure also lets the 1926 women function as both mystery and mirror, so that solving one vanishing means confronting the possibility of another playing out in real time.
Response to The Unknown has been divided in ways that track closely with how readers already feel about Sager’s twistier instincts. Fans of his blend of gothic dread and slow-build horror have called this one of his most purely atmospheric books yet, praising the confidence with which he holds two timelines in tension without letting either go slack. Others have felt the plotting leans too hard into misdirection, piling on reversals that serve the shock of the reveal more than the emotional throughline of the characters, and that the ending doesn’t fully earn the dread it spends the whole book accumulating. Even the more skeptical notices, though, tend to credit the setting and mood as some of the strongest atmospheric work of his career.
The Unknown is best approached as a mood piece first and a puzzle box second. Readers willing to let the island’s fog and the weight of its history do the work will get the most out of it; those hunting for an airtight mystery may come away feeling the knots were tied more for effect than for meaning. Either way, it’s a confident, creepy entry from one of commercial fiction’s most reliable purveyors of gothic suspense — and a strong pick for anyone looking for an unsettling read as the nights start getting longer.
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