Well before we met, I felt as if I knew Karen Thompson Walker. Though this wasn’t true, it didn’t seem entirely delusional: Portland, Ore., is a small town; we have a dear friend in common; and, three months ago, I’d had lunch with her husband and older daughter at a large writerly gathering at a local brewpub. Thompson hadn’t attended, perhaps because it was blisteringly hot that afternoon, or perhaps because she had a six-month-old baby at the time, and instead seized a chance to get some sleep.

Sleep, the holy grail of the new (or, in this case, repeat) parent, is the subject, in a way, of Walker’s haunting, hypnotic second novel. The Dreamers (Random House, Jan. 2019) takes place in the fictional Southern California mountain town of Santa Lora, where a sickness descends one evening in early fall. A first-year student at the local college leaves a party, goes to bed, and then doesn’t wake up; a few days later, she’s dead. Soon after, another girl falls asleep. She doesn’t die, but nor can she be roused. Though the college attempts to quarantine the students, the sickness spreads, first among the residents of a dorm and then outward: to the janitor who cleaned their rooms, to a clerk at a convenience store, a backpacker, and a young bride, and soon to the doctors and nurses caring for the sick teens, who sleep “like children, mouths open, cheeks flushed. Breathing as rhythmic as swells on the sea.”

As if the creep of a mysterious sleeping sickness weren’t eerie enough, the world around Santa Lora seems to shimmer and vibrate with threat. The mountain lake is vanishing, the region is prone to earthquakes and landslides, and the forest is “fertile for fire.” As Walker’s compassionate, omniscient narrator asks, “What if misfortune can be drawn to a place, like lightning to a rod?”

When Walker and I finally meet, outside a pie shop, she has a brilliant smile and a happy, bell-like laugh. A former editor at Simon & Schuster, she is now a professor at the University of Oregon in Eugene, two hours south of Portland. Thankfully, when I tell her that I’m convinced I know her already, she doesn’t seem to find this very weird.

On this sunny fall Friday, over the sound of clinking porcelain, as the ice caps melt and the world veers toward autocracy, Walker explains that she took inspiration from Jose Saramago’s novel Blindness, about an epidemic, and his careerlong fascination with “the possibility of the impossible.” For Walker, the line between what is possible and what’s not is “the richest territory” for fiction, in part because the pressure of a catastrophic force serves to illuminate the quotidian. Her bestselling debut, The Age of Miracles, imagined the slowing of Earth’s rotation and the cataclysmic disruptions this causes for all planetary life—but also, just as powerfully, it chronicled its adolescent narrator’s charged, complicated coming-of-age. The Dreamers employs similar psychological realism and a disaster that’s far less sci-fi: point of fact, there’s a “mystery illness” in the headlines on the very day we meet.

When I point this out, Walker laughs her fine laugh again. “Maybe another reason I’m so interested in that particular quality of realism is that I’m someone who’s quick to worry and fear,” she says. “And writing is a way of exploring anxiety and frightening scenarios in a way that’s satisfying, instead of just horrifying.”

And contagion stories in particular, Walker notes, are compelling because of the way “they inevitably reflect human connections and human bonds.” In a plague novel, it’s the outsiders—another favorite subject of hers—who stay safest. That’s because, as The Dreamers tells us, the sickness travels most easily “through all the same channels as do fondness and friendship and love.”

When Walker began writing The Dreamers, she didn’t know what her sickness should look like—a flu, first taking hold in a college dorm, perhaps. She was living in Iowa City at the time, while her husband was enrolled in the MFA program at the University of Iowa (Walker’s MFA is from Columbia). But one night—and here is the magic thing, “the thing that seems too good to be true,” she admits—the idea for the disease came to her in a dream. “When I realized that sleep would be the main symptom of this strange sickness,” she says, “I knew I’d arrived in my favorite fictional territory: those places in human experience where the uncanny or the extraordinary exists rights alongside the everyday.”

In the everyday of The Dreamers, sisters and couples fight, children trick-or-treat, bonds form and break, and “a secret cluster of cells” implants itself in a sleeping woman’s womb. The present-tense narrative telescopes in and out, pulling back to give a panoramic view of the situation, then zooming close as individual, intimate stories play out against the backdrop of the crisis. The disease is determined to be airborne, and soon the entire town is cordoned off. In the outside world, conspiracy theories abound; within, the dreamers’ brains show “more activity... than has even been recorded in any human brain—awake or asleep.”

Walker gives us numerous carefully drawn characters in The Dreamers, but she began this novel, like her first, not with a person, but with a question: what if sleep became contagious? Or, as in The Age of Miracles, what if “light became unhooked from day, darkness unchained from night”? What would happen in such unprecedented circumstances?

Walker cites Kazuo Ishiguro’s Never Let Me Go as “a master class for me in how to blend speculative elements with psychological and emotional realism.” Marilyn Robinson’s Housekeeping and Julie Otsuka’s The Buddha in the Attic were also influences, she says, and Ann Patchett’s Bel Canto served as a model for how to follow a large cast of imperiled characters.

The heady premise of The Dreamers allowed Walker to investigate the complexities of consciousness, the foundations of morality, and the very nature of what we understand to be reality. But if that sounds grand and cosmic, there is also the tiny sweetness of a father teaching his baby new words (“This is our shadow, yours and mine, long on the sidewalk because the sun is low in the sky at this time of year”) and the hesitant flush of new love (“Here he is beside her. Here is his hand, laced in hers at the end of the day”).

And here, in this Portland café, there is the chatter of neighboring tables, the steamy hiss of the cappuccino machine. There’s the sun shining outside, and soon it will be the weekend, and, in a few days, Walker will write to say that she got the sickness she didn’t use in fiction: a stomach flu. But—spoiler alert—unlike a handful of her characters, she very quickly gets better.

Emily Chenoweth is the coauthor, with Johnny Marciano, of Klawde: Evil Alien Warlord Cat, forthcoming in February.