“We are each other’s harvest.” For the people of the fictional city of Lucille, these words, written by the poet Gwendolyn Brooks in homage to the great Paul Robeson, are the battle cry of their revolution. “We are each other’s business; we are each other’s magnitude and bond,” the verse continues. In Akwaeke Emezi’s beautiful, genre-expanding debut young adult novel, PET (203 pp., Make Me a World, $17.99; ages 12 and up) — a finalist for a National Book Award — the lines serve as both a clarion call and a reminder that utopian communities like Lucille are not only created, they must be fought for and maintained.

At the center of “Pet” is 15-year-old Jam, a trans girl who is loved and protected by her family, and an entire city. Lucille is more than a safe space for Jam. The city represents a sacrifice redeemed, a battle won — but not forever. Emezi opens “Pet” with an evocation of the struggle of good against evil. Once there were monsters everywhere in Lucille. There was a revolution and, in the end, the angels won. We’re reminded of the simplicity of it all: Monsters hurt people, angels can save us. Yet this idea also underlies the novel’s poetic complexity. We all know what monsters are, but, as Emezi puts it, “when you think you’ve been without monsters for so long, sometimes you forget what they look like.”

[Read our Q & A with Akwaeke Emezi]

The story eases into action when what appears to be a hideous chimera painted by Jam’s mother, Bitter, is conjured out of a two-dimensional canvas by a drop of Jam’s blood, landing in the seemingly perfect world of Lucille. The eyeless figure, complete with claws and horns, calls himself Pet. Thus begins a tender friendship between a monster and a girl who together set out to hunt a real monster, in a place where the angels have supposedly eradicated them all.

Jam, for her part, unwaveringly defines the parameters of her own existence. She is selectively mute, choosing to communicate in sign language and use her speaking voice only when necessary. At the age of 3, after being repeatedly misidentified as a “handsome little boy,” she exclaims that she is “Girl! Girl! Girl!” Aloe, her doting father, acquiesces by simply stating, “We didn’t know.” Hormone blockers and treatments ensue, followed by surgery when she turns 15, all with the support of her loving parents and the acceptance of her community.