The following version of this book was used to create the guide: Duncan, David James. Sun House. Little, Brown, and Company, 2023.

Jamey Van Zandt is born in 1958 in the city of Portland, Oregon, and endures a difficult child after his mother passes away on his fifth birthday. As Jamey grows and wrestles with his trauma, he develops a keen interest in theater, and winds up pursuing a career as an actor in spite of his father's initial trepidation. Meanwhile, a young woman named Risa McKeig begins studying Sanskrit literature at the University of Washington in Seattle. In spite of her passion for these Vedic texts, Risa struggles to confront the void that her father's long absence from her life has opened in her, and eventually drops her Sanskrit studies upon determining that their precepts are sexist.

In the town of Pipestone, Colorado, a woman named Lorilee Shay and a man named Trey Jantz fall in love atop Two Medicine Peak when Lorilee reads Trey a passage from a Gary Snyder poem. Their humble lifestyle causes problems for them, however, and their marriage quickly grows strained at the same time as Pipestone begins to suffer from the effects of pollution. Trey makes various fumbling efforts to win Lorilee back, including procuring a signed copy of Snyder's collection, a gesture that ultimately leads to him and Lorilee conceiving a child, Japhy. However, the marriage eventually disintegrates, and Lorilee sells her copy of Snyder's poetry for a meager sum.

TJ McGraff, a Jesuit missionary, returns from his post in Mexico after several years of religious work to discover that his brother, Jervis, has managed to turn their inheritance into multiple millions of dollars. TJ uses this money to open a series of restaurants, an endeavor that appears to be going well before Jervis is assaulted by several men behind a dumpster and falls into a coma. Meanwhile, Risa begins dating a man named Grady Haynes, whose interest in philosophy is far less keen than his interest in sleeping with Risa, a detail that begins to put strain on their relationship. When TJ calls Risa, his close friend, and asks her to take over his businesses while he grieves alongside Jervis, Risa agrees, and Grady exits their relationship in order to hike the Elkmoon Mountains in Montana. Eventually, TJ uses some dolls he was gifted in Mexico to perform a prayer that awakens Jervis from his coma.

Upon recovering from his coma, Jervis begins communing with a deity he calls Ocean and obeying her instructions so as to bring aid to various suffering people on the streets of Portland. Meanwhile, Risa moves to Providence, RI, in order to pursue an MFA and meets a handsome but spiritually unengaged man named Julian Ventano there. Lorilee, attempting to reclaim space for herself in the wake of her divorce, decides to hike Two Medicine Peak with some assistance from her neighbor Walt Steitz, a journey that reignites Lorilee's interest in music and inspires her to write several songs on her dulcimer. When Risa finishes her MFA, she relocates to Portland with Julian, but breaks up with him after having a chance encounter with Jamey, whom she instantly falls for.

Grady begins hiking the Elkmoon Mountains and receiving wisdom, advice, and insight from a grizzled mountaineer named Gladys Wax, who informs him of a secretive people called the Lûmi who function as protectors of the Elkmoons. Meanwhile, Risa's father passes away and she decides to travel to Montana to scatter his ashes in the Elkmoons, where he was born. When she arrives, Risa discovers that her father's homeland has fallen into possession of a holding company called NorBanCo who hopes to turn the plot into a tourist attraction. Eager to preserve her father's home, Risa teams up with the local ranchers, including Kale Broussard and Lou Roy Skinner, to strategize how to protect the Elkmoons from development.

Risa loops TJ and his considerable financial holdings into her plan, and he enthusiastically agrees, in part because Jervis has received a vision from Ocean foretelling the creation of a community in the Elkmoons. Lorilee stumbles upon the community while touring her new album and, alongside Japhy (who has begun going by "Mu") agrees to assist the residents of the Elkmoon Valley in their efforts at resistance. Grady leaves his job in Portland to become a resident of the Inner Elkmoons for the entire summer, establishing a base camp near Jade Lake, a holy site located in the upper reaches of the range. When Risa returns to Portland to bid a final farewell to her community there, she again encounters Jamey, and the pair initiate a romantic relationship.

Upon learning that she has developed breast cancer, Lorilee decides to hike to the Inner Elkmoons on the advice of a man named Sam Rock, and has a spiritual experience in Jade Lake. However, the area is beset by storms, and Lorilee suffers a horrible ankle injury after being blasted by a lightning strike, prompting Grady to emerge from his shelter and nurse her back to health. The same storms catch the woods of the Elkmoon Valley on fire and devalue the land so totally to the developers at NorBanCo that they vacate it, allowing the community to assume the land's control. Grady manages to ferry Lorilee down the mountain, but she begins to wither away in the years that follow, and eventually passes peacefully out of life.