The library is sinking. The patrons don’t mind, or at least don’t complain to Joyce, and she doesn’t complain to them. The library’s second-floor windows once overlooked a green prairie dotted with brightly painted homes and arrow-straight roads. Now, those windows are level with ashy ground (the first floor buried altogether) and there are no more homes, no more roads, only a gray, muddled landscape pockmarked with house-sized pits. Nobody asks what Joyce will do when the library is gone. It’s the last library. She’s the last librarian.

Each morning, she unlatches the windows and watches the patrons emerge from their burrows. They lead their children across a dust-strewn landscape, clamber across the windowsill, and use one of Joyce’s dry paintbrushes to whisk the dust from their sleeves and skirts. Joyce catches the children’s eyes and, with a jerk of her chin, has them wash their hands. She doesn’t tolerate slovenliness.

The buried first floor houses the fiction collection, the picture books, the community room. It’s cooler there, sheltered from the bleached, cloudless sky. During the unbearable heat of afternoon, Joyce wanders the stacks with a damp cloth draped about her thin neck, her hair in a knot. Her friend Alejandro keeps offering to cut her hair, but the last time he left her with gray, uneven spikes—a deranged topiary.

Alejandro prefers the second floor despite its heat. The light is better there, and he can study the narrowing horizon through Gothic floor-to-ceiling windows. In the Maps Room, he compares the landscape with local plats, old zoning plans, geological tables. He thumbs through atlases to see how countries emerged and disappeared, how borders snaked one way then dissolved, how on the oldest maps, beasts with grasping tentacles lurked in uncharted corners.

Sometimes there’s no horizon. Sometimes, the entire landscape is swathed in swirling gray like television static. Or snow, Joyce thinks, though she can’t remember if she’s seen snow or not. She sometimes remembers trees. She sometimes dreams of mountains.

Alejandro attempts his own atlas. It’s difficult work: his hand is liver spotted and arthritic, is nerve-damaged from his time in California when he was a child; he can barely open it beyond a claw-like C. He starts with a rectangle for the library then, above it, draws two lumpen circles—ancient holes where once a government stored building-sized missiles in case it needed to commit atrocities. Below it, the freeway, or what’s left of it, a drooping east-west line. He’s drawn a blank-eyed face, he realizes. The mouth thin and judging; the rectangular nose crooked and canting.

Below him, Joyce frowns at the grime gathered on books that haven’t been checked out in over a decade. Her orphans, she calls them, and wipes away tendrils of mold that now grows all along the lower level. It blackens the carpet, creeps up the walls, leaves the air tasting damp and loamy, like bracken and pill bugs and crickets, like disappeared things.

Another earthquake pulls the library down an inch. Children test out muffled shrieks and giggles; parents press fingers to lips. But Joyce is too busy rearranging her fallen orphans to shush them, too busy to notice the parents slipping books into purses and backpacks and shirts. As they tumble out the window with their spoils, the library lurches again then sits quietly, blankly.

Alejandro stands on the prairie and raises his thumb toward the library. He tries to triangulate the distances of the exiting patrons though he was never very good at math. The patrons totter forward in groups of two and three, then disappear, and Alejandro demarks each vanishing with a square until he maps out a jagged, contented smile of pits curving beneath the library.

Night falls. The library sighs and extends its roots. They stretch further and further for hidden aquifers, feeling their way like blind fingers. They grab at rock, crush buried fossils, and pull the library deeper into the coolness of the subsoil. There it vibrates and hums and dreams of rain.

The second-floor window is half-buried now. When Joyce opens it, soil spills inside. Soil and dust and a scent of ozone, and Joyce remembers rain even though it’s been years since she’s felt it on her face, years since she’s stepped outside. How much longer, she wants to ask the patrons. How much longer until they can no longer squeeze through the window’s shrinking gap, until she herself is trapped within. Instead, she tells them to wipe their feet. Instead, she leaves the window open.

Alejandro shows Joyce his latest map and points out the homes, the service stations, the bowling alley on Maple—all buried. The consignment shop, the corner pharmacy, the clinic he used to drive his wife, back when he had a car, back when there were roads. He sometimes dreams of driving. Of wheat fields. Of telephone poles racing past his window. He sometimes finds the tops of poles spiking up from the earth, their cracked insulators bleached white like knuckle bones. He marks them on his map. He marks the map again when they disappear.

Joyce packs her orphans into a shopping bag and fumbles with the laces of her husband’s old work boots. They’re too big for her and leave broad, treaded tracks across the gray plain. In one hand, she carries Alejandro’s map; in the other, a walking stick just long enough to rap on the roofs of sunken houses. When there’s no answer, she makes an X on the map and goes to the next until someone opens their hatch and gazes upward, their hand outstretched.

Alejandro throws one stiff-kneed leg in front of the other counting out the paces between buried artifacts: here, an aerial antenna; there, the broken bricks of a chimney; in the dust, bent and swaying, a windmill’s rusted blade; and beyond, Joyce’s stooped silhouette penciled against the sky. Each evening, she returns with fresh notes to add to his maps—which houses are empty, which holes have vanished—and he helps her count how many books she delivered, how many she has left. There are too many, he thinks, and sometimes he thinks there aren’t nearly enough.

Midnight, and the library gasps and shudders and releases a flurry of spores, smaller than dust. They catch and sparkle in the starlight like an aurora borealis, then swirl and settle across the prairie. There they glow, their light softening the nearing horizon, diffusing it until it’s gauzy and translucent and doesn’t look dangerous at all.

Joyce sleeps on her office’s tattered couch, her head pressed into an oily throw pillow. Behind her, fingers of mold stretch from floor to ceiling, carving out runnels in the faded drywall, creeping into channels of the ceiling’s acoustic tiles. She no longer wipes the walls clean, no longer notices when the spores lose their grip and rain down upon her coverlet, the one she crocheted beside her husband in his hospice room. His photograph sits beside the couch. Mold darkens its corners, fades his eyes.

Alejandro sleeps directly below, in the maintenance closet where pipes gurgle and rattle behind his head. There used to be only two, he’s sure of it, but now five pipes snake upward into the darkness, clanking and hissing and pulsing with heat. When he puts his ear to them, they go silent, as if embarrassed, as if holding their breath, and he can only hear a distant churning like the roar of waves. Then he remembers the ocean, sand, a woman in a floral swimsuit telling him to stay close, and even then, at the edge of it all, the smell of smoke.

Joyce helps Alejandro decipher his maps’ legends, rendered with crayons in Alejandro’s shaky scrawl. We’re over the cemetery, she says at last, and points to a line of orange dashes where rows of toothlike headstones once stood. They were some of the first to go, sucked down into the gummy soil as if gathered by the dead, gone before the living noticed. Joyce kneels and begins to dig. When the hole is large enough, she lays the last orphan inside, then covers it up again, and pats the ground smooth.

Dusk again. Alejandro helps Joyce push a study carrel beneath a transom window, the only window they can climb through now. Joyce’s bag is heavy. Now that the orphans are gone, she’s emptying the shelves of fiction and poetry, science and history. One night, she delivered twenty-six encyclopedias while Alejandro mapped new quadrants, paced out new hectares. Now she lowers her walking stick for him and helps him shimmy out the window. The air beats close against them. A storm is rising. This way, Alejandro says, his map unfurled.

An ashy grit lashes their legs. Joyce leans over Alejandro’s map and makes corrections until they find the house, rap on its roof, and deliver the books. That’s the last house, Alejandro says and adds a tick to his map. The wind whips his words around and catches Joyce’s bag. It’s empty. It flies free from her grip and takes off into the sky. It flutters there a long while, then vanishes in the gathering clouds.

They return to the library, stopping by one of the missile silos on their way. The wind blows across its aperture with a throaty hum. How deep do you think it is? Alejandro asks. Joyce shakes her head and pulls out a ring of keys to forgotten doors—to her old house, her postbox, a large brassy one to the library’s buried entrance. The key ring arcs into the darkness, catches the last light of the prairie, then winks away. They wait and listen. Don’t hear it land.

It’s almost afternoon, the light dull and fleshy through mold-spackled windows. Alejandro has to squint to make out the last pages of his map laid before him. Joyce helps him tape the pages together and spread it across an expanse of floor where children once sat for story circle. The rest of the library is empty, skeletal. Around the edges of the map, Joyce has drawn a sea serpent, its long neck arching upward. Then the neck wavers, the library groans, the empty shelves shake and shake.

Darkness sifts about them. A papery scent fills the room. The windows, Alejandro says, and Joyce nods in the dark though of course Alejandro can’t see her. She reaches out for him, finds his withered hand. It is small and wizened and fits in her palm. The windows, they’re buried, she says into the darkness. Then, one by one, small grains of dust begin to glow, soft and inviting as sleep. They settle onto Joyce’s face, onto Alejandro’s broad nose. Oh, she says, and squeezes his cool, dry hand, and she holds on—they both do—as the light of the dust fades from green to mauve to nothing. And there they sit, quiet and unmoving, listening to the library’s slow, contented breathing. Outside, sheets of lightning streak across the prairie toward an unbroken horizon, but there is no thunder.