Lydia is a 32-year-old bookstore owner living in Acapulco, Mexico. She enjoys a comfortable, middle-class life until cartel violence abruptly forces her to flee her home. Fiercely protective of her son, she uses her intelligence and survival instincts to traverse the dangerous migrant route north to the United States.

Sebastián is a dedicated and principled journalist working in Acapulco. Despite the escalating danger in his city, he refuses to abandon his commitment to exposing cartel corruption and violence. His unyielding journalistic integrity makes his family a target, directly triggering the story's violent opening sequence.

Luca is Lydia and Sebastián’s eight-year-old son, a brilliant boy with an innate talent for geography. Traumatized by the sudden violence at home, he adapts to the migrant route with quiet endurance. He wears his father's red Yankees cap as a constant source of comfort during their dangerous travels.

Javier, known as 'The Owl', is the 51-year-old jefe of the violent Los Jardineros cartel. He maintains a sophisticated, thoughtful exterior while operating as a ruthless criminal. He seeks terrible vengeance against Lydia's family after a tragedy strikes his own, transforming from a trusted confidant into a relentless pursuer.

Lorenzo is a 17-year-old sicario associated with the Los Jardineros cartel. Having joined the cartel at a young age after being driven from his home, he presents a menacing presence along the migrant trail. He wants to leave his cartel life behind, a desire that endangers the migrants he encounters on the road.

Rebeca is a beautiful, 14-year-old Ch’orti girl fleeing violence in Honduras with her older sister. Physically and emotionally fragile, she struggles with the terrors of the migrant route while offering quiet comfort to younger travelers. She relies heavily on her sister for protection.

Soledad is a 15-year-old Ch’orti girl from Honduras, traveling north to escape a violent gang member. As the older sister, she assumes total responsibility for Rebeca's safety. She remains highly vigilant and physically defensive throughout their journey.

Beto is an outgoing, resourceful ten-year-old deportee born in Mexico but raised in the United States. He travels alone to return to the only country he considers home. He possesses extensive street smarts, understands border politics, and carries a surprisingly large amount of cash. He suffers from severe asthma.

Juan Pedro, widely known as El Chacal, is a 39-year-old coyote with a strong reputation for keeping migrants alive. Drawing on his intimate knowledge of the desert, he issues brusque, authoritative commands to ensure his group survives the brutal elements and border patrols.

Marta is Javier's beloved teenage daughter. Kept entirely in the dark about her father's true profession, she represents the only innocent and pure aspect of his life. Her tragic reaction to the truth drives the central conflict of the narrative.

Marisol is a mother who was recently deported from California after living there for sixteen years. Separated from her American-born daughter, she provides Lydia with sobering insight into the realities of the US immigration system and the cruelties of family separation.

Carlos is Sebastián’s former college roommate. Living with his American wife, he provides Lydia and Luca with crucial temporary shelter and safe passage in a church van during their initial flight from the cartel.

Meredith is Carlos's devout American wife. She is heavily involved with her church and missionary work, though her somewhat naive perspective on the dangers of Mexico occasionally clashes with the harsh realities Lydia faces.

Elmer is Soledad and Rebeca's father, living in San Pedro Sula. He takes his daughters in after they flee the cloud forest, but inadvertently becomes a target of the violent gang member pursuing Soledad, highlighting the inescapable reach of gang violence.

Iván is a violent gang member in San Pedro Sula. His relentless abuse of Soledad and subsequent interest in her younger sister, Rebeca, serve as the terrifying catalyst that forces the sisters to begin their journey north.

Ricardo is a doctor who embodies the novel's theme of the kindness of strangers. Motivated by his deep Christian faith, he risks his own safety to provide medical care, food, and shelter to migrants traversing dangerous territory in Sinaloa.

Padre Rey is a dedicated cleric running a sanctuary for migrants. He provides a brief, desperately needed haven of safety, food, and rest for those traversing the dangerous route through Mexico.

Hermana Cecilia is a nun who assists in running the migrant shelter. While providing a safe space, she remains pragmatically aware of the dangers within the migrant community, advising travelers to be cautious about whom they trust.

Choncho is a fellow migrant attempting to cross the Sonoran Desert with his brother and teenage son. He is a supportive presence during the grueling trek, frequently attempting to lift the spirits of the group during moments of extreme physical hardship.

Ricardín is Choncho's teenage son, undertaking the brutal desert crossing. His presence highlights the extreme physical perils of the environment, particularly when severe weather strikes the migrants during their trek.

Slim is a migrant attempting the dangerous crossing through the Sonoran Desert. He travels closely with his brother and teenage nephew, relying on the coyote to guide them safely through the brutal environment.

Nicolás is a former PhD student at the University of Arizona who was deported after missing routine immigration appointments. Highly educated, he provides the group with grim warnings about the dangerous wildlife and harsh realities of the desert terrain.

Néstor serves as a helper at the Casa del Migrante. He actively assists in maintaining order and safety within the sanctuary, standing alongside leadership during disputes with aggressive individuals.

Yénifer is Lydia and Sebastián's fifteen-year-old niece. She attends the family quinceañera cookout in Acapulco, where her life is cut violently short. Her memory deeply influences Lydia's later interactions with teenage migrants.