The next thriller from #1 bestselling author Sarah Pekkanen combines a decades-old mystery with spine-tingling paranormal elements in this twisty novel of the seen and unseen.

Extrasensory perception.
The Gift.
A Sixth Sense.
Or something else....

In 1964, four remarkable young women at a prestigious university became the subjects of parapsychology experiments by a visionary scientist. On the cusp of a historic breakthrough, the women mysteriously vanished and the program was erased from history.

Decades later, Riley Bell, newly divorced and desperate for a fresh start, accepts a caretaker job for an elderly widow named Betty. Riley steps into a home that is frozen in another era - no microwave, television, or cell phones, and Betty has never heard of the internet.

Why has Betty lived in such profound isolation for so many years, and why does she need Riley now? As the story unfolds across two timelines - Betty's 1960s era of 5 o'clock martinis and high-stakes experiments, and Riley's quest to uncover the truth about the missing women - old secrets rise to the surface. And the only way to survive is to confront the mystery that has lingered for sixty years.