As the propulsive "American Dirt" opens, Lydia and her son Luca cower on the tile shower floor in Lydia's mother's house in Acapulco, Mexico, while gunmen murder their entire extended family. From this hail-of-bullets beginning, the pace of Jeanine Cummins' first novel never slackens as Lydia struggles to lead her son to the safety she imagines they will find across the border in the United States.

The perpetrator of the massacre is Javier Crespo Fuentes, the leader of a dominant cartel. Lydia befriended Fuentes before she knew his identity, as he was the best customer at the bookshop she owned. Then Lydia's journalist husband Sebastián wrote an exposé about Fuentes for the newspaper where he covered the descent of Acapulco into cartel violence. "The year before Sebastián's murder, Mexico was the deadliest country in the world to be a journalist, no safer than an active war zone," Cummins writes. Lydia and Luca must attempt to flee without attracting the notice of Fuentes' myriad associates.

Cummins is a skilled and empathic chronicler of trauma and its aftermath, in part due to unfortunate personal experience detailed in her memoir "A Rip in Heaven." She writes in an afterword, "When I was sixteen, two of my cousins were brutally raped by four strangers, and thrown off a bridge in St. Louis, Missouri. My brother was beaten and also forced off the bridge."

Cummins is so attuned to the emotions of the traumatized that she evokes these feelings in the reader. As Lydia and Luca make their way north, complications arise from avoiding credit cards, ATMs, and cellphones that the powerful kingpin could use to track them, producing a cascading series of cliffhangers that don't make it easy to sleep after reading a chapter without Lydia's survival tactic: "She directs her thoughts toward blankness. She does this exercise with authority, and her mind obeys. She repeats this over and over: don't think, don't think, don't think. And because of this self-control, she moves mercifully toward sleep."

The once-privileged Lydia and Luca must travel the treacherous route that impoverished migrants follow, hopping freight trains known as "La Bestia" that maim and kill many riders. Cummins creates a convincing array of characters, from sisters fleeing Honduras after their beauty makes them gang targets, to a junior member of Fuentes' cartel who claims he's quitting gang life, to a strapping man named Danilo in Guadalajara who calls himself "the guardian devil for migrants who pass through my little neighborhood," protecting them from harm.

While the reader roots for Lydia and Luca to attain their goal, I had a sinking feeling as I read. Given the recent separations of families at the border, deaths of migrant children due to inadequate medical attention, and the rerouting of asylum-seekers to Honduras, is there hope for survival or a promise of anything better waiting for them if they arrive in the United States?

"American Dirt" is an unsettling and immersive story, fueled by the elemental love of a mother for her son that causes her to flee everything she's known in her desperate quest for survival.

Jenny Shank's novel "The Ringer" won the High Plains Book Award. She teaches in the Mile High MFA Program and her work has appeared in McSweeney's, Washington Post and the Atlantic.

American Dirt

By: Jeanine Cummins.

Publisher: Flatiron Books, 386 pages, $27.99.

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