Caves have always given me the creeps, but thanks to Caitlin Starling’s The Luminous Dead (Harper Voyager, 2019), they now terrify me.

Starling’s debut novel takes readers along with her young protagonist, Gyre Price, to a place that I think few would voluntarily go—into a deep, pitch-dark cave inhabited by avalanche-inducing, rock-eating worms from which only one human being (among many explorers) has emerged alive.

Gyre thinks the risk of scouting for minerals is worth it because the job pays so well that it will allow her to escape her home planet (a godforsaken mining world) and search for her missing mother. In addition, she’s wearing a state-of-the-art suit, which protects her from the cave’s potentially lethal environment.

What she doesn’t count on is Em.

Normally, there’s a whole team of experts guiding cavers like Gyre, but when she’s deep underground Gyre learns her team consists of only one person, a woman named Em, who owns the mine but whose motives and reliability become increasingly murky as the days pass.

“The more that it is only Em there with her, the worse things get because Em isn’t sleeping, Gyre isn’t getting to talk to anybody else …, and they’re getting more and more drawn into each other’s problems as opposed to it being a professional sort of interaction,” Starling says.

Gyre knows Em only by voice and an occasional video transmission, and yet they form a profoundly intimate—and arguably twisted—bond. It perhaps comes as no surprise that Starling was a teen in the 1990s, forming intense online relationships with people she never met in person. “It’s very easy to construct ideas around who that person is and what your relationship is like that can become very tumultuous or intense,” she says.

With a single setting and only two main characters, one of her biggest challenges was keeping the plot propulsive. Fortunately, with corpses of dead cavers appearing in unexpected places, massive worms threatening to bury her, and the ever-present possibility that rather than help Gyre, Em wants to kill her, Starling meets that challenge with page-turning ferocity.