The following version of this book was used to create the guide: McBrayer, Lauren. Like a House on Fire. G.P. Putnam's Sons, 2022.

Like a House on Fire begins in the San Francisco metro region, where a woman named Merit decides, after several years of working as a stay-at-home mother while aspiring toward a career in painting, to seek employment at an architectural firm called Jager + Brandt. She is immediately hired by Jane, an imposing, forthright, and powerful architect at Jager + Brandt who seems to take a liking to Merit. Their initial meetings go well, although Merit finds herself in a touchy social situation during her first lunch with Jane when the mention of children causes Merit to spontaneously lactate. While Merit settles into her new position at Jager + Brandt, her relationship with her husband, Cory, begins to flag, a circumstance made worse when Cory fails to adequately contribute to the birthday party that they throw for their son Nash. When Jane suggests that Merit and Cory should come eat dinner at her husband Edward's restaurant, the evening sees the two women sequester themselves from the two men and resolve after the fact not to invite them to future meetings.

Only a few months into Merit's tenure at Jager + Brandt, Jane offers her the opportunity to take the lead on a renovation of a historic Painted Lady home for a lesbian couple named Allie and Regina. Merit eagerly agrees to the assignment, but things go awry when Regina manages to use the extramarital affair she is having with Lars Jager to strong-arm Merit into approving the destruction of a historic fireplace in the home, something Merit specifically promised Jane she would not allow. Jane is so furious with Merit that Merit nearly resigns from her position, but the pair manage to patch up their relationship, particularly after Jane confides in Merit that she has discovered Edward is cheating on her. Merit becomes pregnant with her third child, but declines to tell Jane this information since she knows Jane is working through a separation from Edward while also enduring a screening process for a tumor that has been found on her breast. While accompanying Jane to the doctor's office, Merit suffers a miscarriage and allows Jane to transport her to a nearby hospital, an event that forges a deeper connection between them while driving a further wedge between Merit and Cory.

About six months after Merit's miscarriage, Cory begins petitioning her to try becoming pregnant again, a proposition that Merit vehemently opposes. Merit also learns that Jane intends to leave Jager + Brandt in order to pursue her own architectural practice, news that devastates Merit, who has begun to rely on her relationship with Jane as the only fulfilling part of her week. After several months during which Jane and Merit see one another only rarely, Merit goes to Jane's house to celebrate Jane's fifty-ninth birthday, a meeting that prompts Merit to begin feeling romantically attracted to Jane upon learning that Jane has had previous sexual partnerships with women. Merit tactfully avoids Jane for some time after this revelation, but eventually comes to the conclusion that her feelings were not a momentary flight of fancy and that she has fallen completely in love with her former boss. Feeling stifled in her relationship with Cory, Merit allows Jane to take her on a romantic vacation to Mexico, where the pair initiate a sexual and romantic relationship and spend a week indulging in the freedom they each feel away from their lives in San Francisco.

Upon returning from Mexico, Jane and Merit fall into the habit of seeing each other every Friday night for a romantic tryst that Cory assumes is platonic. Meanwhile, Cory takes Merit off guard by suggesting that the family take a vacation to Hawaii, a gesture that is uncharacteristic of the typically money-conscious Cory. Although Merit agrees to go on the trip to Hawaii, she finds herself overwhelmed by the whiplash of her back-to-back vacations, the other of which she found significantly more nurturing than the humdrum visit her family takes to their Hawaiian resort. Merit begins to avoid interactions with Cory and her family in order to enshrine her Friday evenings with Jane as a regular happenstance, and even shuts down Jane's concerns about the message this might send by insisting that their time together is the most important thing to her. Things come to a head when Cory takes Merit out to dinner for her fortieth birthday and announces that he has purchased her a house in Redwood City without asking for her input, a gesture that is intended to be romantic but that instead causes Merit to inform Cory she wants to reevaluate their relationship.

The night after her tumultuous birthday dinner, Merit goes to Jane's house and takes comfort in the security and safety she feels while spending time with Jane. The pair flip through old photo albums and dream of a universe in which they met before marrying their respective husbands, but are rudely interrupted by a phone call from Cory informing Merit that her father has passed away. Merit gathers herself and flies to Pensacola, Florida in order to spend time with her predominantly right-wing family, a visit that tears Merit apart because it forces her to confront the full heft of her infidelities. When Merit returns to California, she meets with Jane in order to inform her that she is not yet prepared to leave Cory, news that Jane receives sadly but gracefully before telling Merit that she is in it for the long haul. Five years later, a photographer with a prominent architectural magazine comes to Merit's house to photograph her and her family, and it becomes clear that Merit has indeed left Cory in order to marry Jane.