Sutton's (Gardenia, 2017, etc.) paranormal YA thriller sees a young woman trapped in an afterlife realm,trying to solve the mystery of her own death.As the story opens, a young woman wakes in a dark, confined space. "Let me out!" she screams before falling into a dirty cavern. After orienting herself, she meets a handsome young man holding an unlit cigar who introduces himself as "no one," adding that "We're all no one." She learns that he goes by the name Smoke; she soon meets another girl named Doll, after her one possession. The young woman has a key around her neck, so this becomes her name. It turns out that a small village of people live in "Under," in homes fashioned from dirt. Nobody recalls their lives before they arrived there, but everyone maintains the markings (or coloration) that they had when they died; chillingly, Smoke has a slash across his throat. When a frightening man named Splinter accosts Key, Smoke saves her, and she goes on to befriend a girl named Ribbon as well as a man named Journal, from whom she borrows books. Yet how did books—and other objects, such as beds—come to be in Under? An even graver puzzle confronts Key when Splinter is found burned to a crisp. In this moody YA fantasy, Sutton offers a propulsive, multilayered mystery: How did her characters reach Under, and what's the tangled nature of their relationships? There's also a quiet sensuality to Key's narration, as when she notices that, "Every line of [Smoke's] body is elegant, and my fear is overpowered by admiration." The plot slowly tiptoes forward as Key receives notes from an unknown scribe; one says, "Swim across the river," which turns out to refer to a "river" of twisted tree roots. Sutton takes this dreamlike atmosphere a step further when Key begins to remember her former existence. More burned bodies appear, details of characters' lives creep in, and pressure mounts for Key to stop the carnage. The superior pacing during the final third makes the ending hit like a slow-motion cannon blast.An excellent supernatural tale with a unique premise and indelible characters.