A “mesmerizing” (Stephen King) supernatural novel about a sinister mindfulness app with fatal consequences from the New York Times bestselling author of The Chill.

In this “taut, creepy techno-chiller” (Paul Tremblay, author of A Head Full of Ghosts), recently laid-off newspaper reporter Nick Bishop takes a humbling job: writing a profile of a new mindfulness app called Clarity.

The app itself seems like a retread of old ideas—relaxing white noise and guided meditations. But then there are the “Sleep Songs.” A woman’s hauntingly beautiful voice sings a ballad that is anything but soothing—it’s disturbing, and more of a warning than a relaxation—but it works. Deep, refreshing sleep follows.

So do the nightmares. Vivid and chilling, they feature a dead woman who calls Nick by name and whispers guidance—or are they threats? And her voice follows him long after the song is done. As the effects of the nightmares begin to permeate his waking life, Nick makes a terrifying discovery: no one involved with Clarity has any interest in his article. Their interest is in him.