In her first journal entry, which is dated September 22 and informally addressed to her therapist, Kate Holland arrives in Greenloop with her husband, Dan, after two days of traveling. Kate’s brother, Frank, arranged their move to Greenloop, but he plans to join them only after returning from a conference in China. Kate describes how strenuous the drive was, primarily because she spent so much time obsessing over the news against her therapist’s advice. Exacerbating her mood was their route, which took them through an industrial farming zone.

Kate goes for a walk on the hiking trail while Dan stays behind to unpack. She spots her next-door neighbor, a friendly older woman, but doesn’t stop to introduce herself. She’s eager to see the “happy” trees in the area, which she contrasts with the hostile gray-brown colors of Los Angeles. This allows her to be more present, which she appreciates because she has obsessive-compulsive disorder. She plucks a berry from a bush after looking it up online. The taste reminds her of her childhood home. Kate feels a sense of belonging in the woods.

The book shifts to the transcript of an interview between radio show host Kai Ryssdal and Greenloop founder Tony Durant. After clarifying that Greenloop isn’t an isolated community, Tony explains what inspired the Greenloop concept: Levittown, which used postwar industrial technologies to quickly develop an affordable suburbia prototype. Tony differentiates Greenloop from its predecessors through its focus on comfortable sustainability, moving away from the connotation that sustainability requires austerity and self-sacrifice.

Tony reveals that he secured funding for Greenloop by leading investors to the site he planned to develop. He discussed how the community would be built almost exclusively from recycled materials and laid out around a central common house. The bamboo surrounding the community helps manage Greenloop’s carbon footprint. All Greenloop houses have solar panels and biogas generators, allowing residents to live independently from any public electric grid. The homes also include a voice-activated “smart home” system that automates energy efficiency processes. Tony argues that the maintenance jobs required to keep Greenloop running optimally will eventually lead to a new environmentalist revolution. While the cost of living in Greenloop is too high for most US citizens, Tony emphasizes that Greenloop can inspire others to aspire to a sustainable lifestyle.

On September 23, Kate and Dan attend a potluck dinner at the Common House to welcome them. They meet their neighbors: Vincent and Bobbi Boothe, vegans who bring homemade vegetable soba and give the Hollands a coconut opener as a housewarming gift; Carmen and Effie Perkins-Forster, who are protective of their adopted nonspeaking Rohingya daughter, Palomino; Dr. Alex Reinhardt, author of Rousseau’s Children, a book arguing that civilization corrupted humanity’s essential goodness; and Tony and Yvette Durant, who invited them to the dinner. Tony’s youthful appearance reminds Kate of how energetic Dan was when they graduated from college eight years ago. She later implies that his energy waned while trying to develop an analogue to Silicon Valley in Los Angeles.

A ground tremor occurs, which the neighbors explain away as typical, given their proximity to Mount Rainier. Kate hides her alarm, feeling that the others are speaking in denial of the danger the tremor poses. Only then does the last neighbor arrive: Mostar, the older woman next door to the Hollands. She was waiting for her tulumba dessert to cool. Dan is the only person excited by the tulumba; no one else partakes in it. After a while, Kate notices how harsh Mostar’s personality is, compared to the rest of the group. Tony introduces Mostar as Greenloop’s artist-in-residence, focusing on glasswork sculptures. Cygnus, the company that finances Greenloop, sponsors Mostar’s residence because it can help advance Cygnus’s 3-D glass printing technology. Mostar’s main project during her residency is a full-scale model of her hometown, implied to have been destroyed during a resource conflict in the 1990s.

Mostar asks Kate why she and Dan moved to Greenloop. Kate tries to discuss her work in finance and Frank’s connection to Vincent, but it’s too boring to distract Mostar from pressing for the answer to her question. Mostar asks Dan about his work. When he answers that he’s a digital entrepreneur, Mostar interprets his answer to mean that he’s unemployed. This embarrasses Kate, prompting Tony to reframe Dan as an artist in his own right. The others support Tony’s answer.

Later that night, Kate can’t sleep and longs to speak to her therapist. She knows she can’t talk to Dan about his listlessness. The following day, she tries to unpack their shelves. He doesn’t get up to help her, instead staying in the living room and listening to 90s grunge music. This angers Kate.

The novel shifts to the editor’s interview with Frank, who has retired from his work as an attorney for Cygnus and now lives in a camp near the Cascade Range. He blames himself for moving Kate and Dan into his Greenloop house to justify keeping it off-market after his last major relationship ended. He explains that Kate blamed their mother for their father’s abandonment and thus was permissive of Dan’s behavior. Frank insinuates that he hoped living in Greenloop would get Kate to leave Dan.

A press release from the American Geosciences Institute announces the impact of federal budget cuts on their early warning systems. The release was published around a year before the Rainier eruption.

On October 1, Kate regrets not being more open with her therapist during their online consultation. She’s still acclimating to her new environment, including the absence of spaces outside her home, like the therapist’s clinic and an office. She turns to the structure of her developing routine for consolation.

Kate’s new routine begins with a morning hike, during which she usually encounters Yvette teaching her online yoga classes. She notes that on one occasion, she bumped into the Boothes, who invited her to join them. Kate has tried to get Dan to come with her, but his responses to her invitations are largely noncommittal. Kate realizes that being around him all the time is something else she’s getting used to, now that she can no longer rely on friends or other spaces to ease tensions between them. She describes feeling “trapped” with Dan in his listlessness, which he’s unashamed to show to their new community.

Kate describes one day when all of Greenloop’s online orders were scheduled for coordinated drone delivery. When a driverless van arrived to bring groceries to the community, Mostar faced the challenge of taking her bags to her house by herself. Kate offered to help, which prompted Mostar to ask why Dan wasn’t out helping with the deliveries. Much to Kate’s embarrassment, Mostar knocked on Dan’s window, beckoning him to come out and help.

Helping Mostar with her groceries allowed Kate to see her sculpture work for the first time, and Mostar explained her 3-D printing system. After Dan returned home, Mostar guessed that he had failed in his business pursuits and didn’t know how to recover from it because of his privileged upbringing. The accuracy of her guess shocked Kate.

Instead of going home, Kate turned to the Durants to avoid confronting Dan. She cried to Yvette, who led her in a meditation session to console her, instructing her to seek Oma, the spirit who guards the wilderness. Oma, Yvette explained, was the basis for the Eurocentric myth of Bigfoot, which Kate knew little about other than pop culture representations. The safety of Oma allowed Kate to purge her emotions. Kate wants someone like Oma to make her feel protected all the time.

Early on the morning of October 2, Dan and Kate awaken when a large tremor shakes their house. They go outside and see that Mount Rainier has erupted. All attempts to reach emergency services fail.

The book shifts to the interview with Frank McCray, who laments that the advanced state of Greenloop’s telecommunications capabilities made them too confident to own basic emergency devices like satellite phones.

Returning to Kate’s journal entry on the day of the eruption, the book describes the residents gathering in the Common House for an emergency meeting. Tony confirms that their telecommunications cable no longer works, but reassures everyone that it should reset soon. As the residents discuss what action measures they should take, Tony urges them to remain calm and wait for the volcanic activity to cease. He adds that the highways will be jammed with people trying to escape nearby cities, as well as emergency services vehicles trying to rush to wherever they’re needed. Instead, they should rely on Greenloop’s systems, which are designed to help them live comfortably through their temporary isolation.

Mostar points out that they have no guarantee of when things will return to normal. She suggests making an inventory of supplies so that they can predict how long they can afford to wait before acting. When the others suggest navigating the woods to call for help, Mostar notes that none of them have any maps of the area, let alone the survival skills necessary to reach the nearest destination. As she emphasizes her point, she tries to force Tony into admitting that they have no emergency or navigation supplies that could help fulfill a more active search plan. Tony puts his faith in emergency services to execute prepared plans for Rainier’s eruption. When Mostar doubles down on her point, the others talk her down.

The book shifts back to Frank’s interview. He describes his attempts to send emergency services to Greenloop. All attempts at contact failed.

Kate’s journal resumes. Yvette implores the group to look after each other’s emotional needs, acknowledging that other people may need emergency services more than they do now. She offers to lead a meditation class dedicated to this intention. Tony similarly offers to listen to anyone who needs to talk. Everyone but Mostar applauds the couple as their leaders. The Durants exchange odd looks before reentering their home.

Mostar barges into the Hollands’ house, urging Dan to learn home improvement skills to fix their malfunctioning home system. She suggests building a private garden in the Hollands’ garage, keeping its existence secret from the others, but emphasizes the importance of maintaining the community’s trust in Kate so that she can broker peace when necessary. After tasking Kate with making an inventory, Mostar reassures her that the work will help distract her as they wait for emergency services to arrive. She and Dan start clearing the garage for the garden.

Two hours later, Kate completes her inventory, which she predicts will last only two weeks. She offers to help Mostar and Dan with the garden, but Mostar insists on dividing labor according to specialized roles. Kate resigns herself to Mostar’s lead, knowing that Dan will do the same.

The book shifts to the editor’s interview with Senior Ranger Josephine Schell, which takes place at Schell’s field office at a Washington ski resort. Schell describes the US as being larger than most people realize. Without technology, most US citizens would find themselves in an endlessly hostile land, just as the Greenloop residents did. She describes the unrest that followed the Rainier eruption, which had many underlying causes, many related to government ineptitude. Using a map, she shows how the civil disturbance that the eruption caused widened the National Park Service’s search sector, stretching it to the limit of its organizational capabilities.

Schell comments that most people who settled near Rainier wanted to transplant their urban lifestyles into a rural setting. While she understands their motivations, she denounces their dream as an illusion that left them vulnerable to natural events and predators.

The chapter begins with Frank’s interview. He explains that Tony operated on the principle of “move fast and break things” (63), which is characteristic of tech entrepreneurs. This leaves them vulnerable to crucial planning gaps, as they focus only on positive outcomes.

The novel returns to Kate’s journal. Listening to the radio, Vincent learns that lahars (boiling mudslides) have obstructed all the nearby routes. On October 3, Mostar asks Kate to attend Yvette’s meditation class so that she can find out if anyone in the community has potatoes. In the class, the women misattribute Mostar’s action plan to Tony, claiming that he saved their lives by keeping them in Greenloop. To maintain the others’ trust, Kate says nothing of her collaboration with Mostar. When she asks the women if they have any potatoes, they claim that they don’t. Bobbi’s behavior is especially suspicious in response to this question.

Mostar tasks Kate with developing a ration plan from their current supply inventory. After Kate finishes a draft, Mostar modifies it, drastically reducing their calorie intake to prepare them for scarcity.

Kate goes on a hike, imagining all the people whom the lahars directly affected. The thoughts of people suffering overwhelm her, though she posits that she’s doing it only to develop her “ego-defense mechanism.” Recalling Mostar’s modified ration plan, Kate uses her phone to scan for edible items in the forest. During her search, she detects a rancid scent and then catches sight of creatures moving quickly nearby, emitting a series of howls and grunts. Kate senses that one of them is looking at her. Rather than panic, Kate calmly returns home and is later embarrassed that she let herself imagine a monster in the woods.

The novel shifts back to Schell’s interview. Schell describes a “Massoud Moment” as any event that reveals its relation to a larger, more devastating event only in retrospect. She derives the name from Ahmad Shah Massoud, a guerrilla leader whose assassination was eventually tied to the September 11 attacks just a few days later. Schell has been thinking of Massoud Moments ever since their search party uncovered animal remains near Rainier. Schell paid them no mind until she read Kate’s journal, causing her to reassess what fed on those remains.