Rene Denfeld is a public defense murder investigator who has gazed fearlessly into the dark parts of people’s lives, including her own. Her 1997 book “Kill the Body, the Head Will Fall” drew on her experience as an amateur boxer who became the first woman to win the Tacoma Golden Gloves title. Elsewhere, she has written about the man she once thought of as her father, who turned out to be a sexual predator: “At nights I slept with Johnny and my mother. . . . What happened in that bed? I cannot remember now, and have never remembered.” By the time she was 15, Denfeld was homeless.

Denfeld’s 2014 fiction debut, “The Enchanted,” is a remarkable novel centered on a death-row prisoner and the female investigator involved in his case. At once terrifying and transcendent, the novel received the ALA Medal for Excellence in Fiction and the French Prix Award. It also set the stage for Denfeld’s breakout 2017 bestseller, “The Child Finder.” That novel introduced readers to Naomi Cottle, a private investigator who specializes in missing children. Set in Oregon (Denfeld lives in Portland), its tone is eerie and dreamy, as readers hear the alternating narrations of Naomi and the abducted girl she hopes to find in the Oregon wilderness.

Naomi Cottle returns in Denfeld’s latest novel, “The Butterfly Girl.” This time, she’s in search of her younger sister. As children, Naomi and her sister were abducted and held prisoner for several years. Only Naomi managed to escape. Ever since, she has been haunted by her sister’s fate: Did she survive to adulthood? Who was their captor?

Naomi focuses her search on Portland. There she crosses paths with Celia, an 11-year-old runaway who has fled sexual abuse at the hands of her heroin-addicted mother’s vile partner, Teddy. Like Naomi, Celia had abandoned her own younger sister when she left home. Celia now takes refuge in a ravine beneath a highway overpass with other homeless children who dumpster dive for food and prostitute themselves for a few dollars or the promise of a hot meal or drugs. During the day, Celia finds solace in the city library, absorbed by natural history books about butterflies. Sometimes, she returns home to check on her sister, Alyssa, and their mother, always leaving before the violent and predatory Teddy returns.

As in “The Child Finder,” the tale unfolds from the perspectives of an imperiled girl; her captor; and the dogged, damaged Naomi. The cynical, steadfast, street-wise Celia does much of the novel’s heavy lifting. Bright and devoid of self-pity, Celia is bent on saving her sister. Having seen her accusations against Teddy dismissed, she steels herself to rescue Alyssa from Teddy’s predations, knowing all too well what she’s up against.

As Naomi observes: “People act as if reporting childhood sexual abuse solved the problem, but Naomi knew that most cases didn’t end in conviction. What no one talked about was what life was like for the victims after acquittal.”

Denfeld reminds us that storytelling remains one of the most powerful means we have of confronting our darkest human impulses, and sometimes overcoming them. It’s unfortunate that this time, while her pacing is swift, her prose, unfortunately, is often workmanlike, lacking the sheer bravura strangeness of the previous novel.

Naomi, intent on both her missing sister and the increasingly vulnerable Celia, too often seems merely diligent than indefatigable. The tale’s resolution relies heavily on coincidences, a few of which strain even a seasoned suspense reader’s credulity. Still, few people write as well about childhood sexual trauma as Denfeld does — its origins, the legacy that can extend for generations for both victim and perpetrator and especially the coping strategies that victims develop to survive.

Elizabeth Hand’s 15th novel, “Curious Toys,” was published this month.

The Butterfly Girl

By Rene Denfeld

Harper. 264 pp. $26.99