Wren, an import liaison at Lionel Garrett Imports, a boutique wine importing company in Manhattan, has spent five years building a career she intends to last a lifetime. At a meeting to prepare for spring buying trips, the company's founder, Lionel Garrett, makes an unprecedented remark about stepping down someday and suggests someone might need to "step up." His minority partner, Jonathan, a man renowned for his brilliant palate, quickly clarifies he has no interest in running the company. Thessaly, one of the top salespeople, blurts out "when?" and immediately regrets it. Lionel deflects, but the seed is planted: The company's future leadership is in play.
Wren and Thessaly occupy very different positions. Thessaly is the daughter of prestigious Sonoma Coast grape growers, raised within the wine world. Her secret ambition is to make her own wine, but her father dismissed the idea years earlier, telling her to "keep learning." Wren grew up in a modest Wisconsin bungalow with an overworked mother and a father who had an alcohol addiction and eventually left the family. She discovered wine while working at a fine-dining restaurant called Heirloom in Madison and was mentored into the industry by a sommelier who connected her with Jonathan. Wren fears her love of wine might reflect inherited addiction rather than genuine vocation, so she monitors her drinking carefully. She views Thessaly with caution and envy; Thessaly has largely overlooked Wren as a "worker-bee type." Gavin, the national sales manager, announces a sales contest tied to the buying trips, with the reward of face time with Lionel.
On buying trips through France and Germany, their rivalry softens into cautious alliance. In Champagne, Wren maneuvers Thessaly into handling tedious administrative work, but Thessaly rises to the challenge. When a producer pours an extra taste of a rare wine exclusively for Wren, the gesture validates her place at the table. Tensions between Jonathan and Gavin surface during the trip: Gavin has aligned himself with Lionel's push for commercial growth, while Jonathan champions artisanal producers. In Germany, visiting the legendary producer Hermann Fuchs, Jonathan's most important partner, Thessaly boldly calls wines made by Hermann's daughter, Elke Fuchs, "empty and mean," contradicting Gavin. Jonathan requests a bottle of Hermann's 1998 Spätlese, a prized late-harvest wine that revives the old man's spirits. Separated from the men at dinner, Wren and Thessaly bond over shared frustration and begin to see each other as potential allies.
Back in New York, they cautiously teach each other their respective skills. Thessaly begins dating Nick, a reserved emergency medicine resident. Wren asks Jonathan directly how to position herself for succession, but he dismisses her ideas, assuring her his personal advocacy will suffice. Gavin approaches Wren about the same producers she pitched to Jonathan, hinting at a promotion she cannot determine is genuine or a trap. Lionel announces a trip to Verona for a select group, framed as a chance to identify his successor.
In the weeks before the trip, Thessaly's drinking escalates as her relationship with Nick deteriorates. She is hit by a car while hungover, and Nick ends the relationship. Hermann Fuchs dies in his sleep, and at the funeral dinner, Gavin produces a rare bottle of Hermann's Spätlese, moving Jonathan to tears. Weeks later, Lionel discovers that Gavin has quit to form his own importing company in partnership with Elke, taking Hermann's entire portfolio with him.
After Gavin's departure, Wren confronts Thessaly about her drinking, revealing her father's addiction and explaining the vigilance behind her own restraint. Thessaly admits she has been drinking too much and agrees to change. Wren proposes they present themselves to Lionel as a team, combining her operational expertise with Thessaly's sales talent. They organize a pivotal dinner with Lionel and Jonathan that goes brilliantly, with Lionel calling them "a truly formidable team." In Verona, however, Lionel names Greg, a younger salesperson he sees as a reflection of himself, as the new director. Devastated, Thessaly proposes they start their own importing company. Wren is skeptical, but Thessaly argues they have the palates, the connections, and the knowledge.
After more than two years of planning, they launch Passerine Imports in Madison, Wisconsin, chosen for its affordability and strong market. They name the company for the common order of songbirds and adopt a bird silhouette as their logo. Their first year exceeds projections, but a philosophical rift emerges: Wren pushes for rapid expansion while Thessaly prefers to stay small. They hire Kara, a Black bartender transitioning into wine sales, as their first employee, followed by Alice, a high-performing saleswoman whose commercial instincts clash with Thessaly's preference for esoteric wines. Wren grows close to Alice, and Thessaly feels increasingly sidelined.
Thessaly begins volunteering on a local farm, finding deep satisfaction in hands-on work that the importing business cannot provide. When Alice is fired after a client reveals her history of under-the-table dealings, and Thessaly's father injures his knee, Thessaly flies to Sonoma to help manage the family vineyard. Her mother, Eleanor, reveals she was the one who prevented Thessaly's father from helping Thessaly start making wine, wanting her to find her own path.
The breaking point comes when Thessaly, on a buying trip in Italy, stays to watch a mobile bottling operation at a producer's winery instead of catching her flight to a Chicago conference where she and Wren are scheduled to present together. Wren delivers the presentation alone. Back in Madison, their argument exposes the core conflict: Wren sees Passerine as her life's work, while Thessaly sees it as a phase before her real calling. Thessaly admits she cannot continue, and they agree not to be enemies.
Wren restructures Passerine as a solo operation and begins a relationship with Martin, a beverage director she met through work. Thessaly returns to Sonoma, where her father gives her a half-acre plot. Her sister, Ari, takes her to Tin City, an industrial park of small wineries in Paso Robles, California, where she meets Lila Czerny, a winemaker her age running exactly the kind of personal operation Thessaly has always envisioned. Thessaly apprentices with Lila, begins making her own wine, and acquires land for her own winery.
Nearly three years after their split, Thessaly invites Wren to visit. Over dinner, she opens the last bottle of a wine she made herself, a deep red labeled with a hand-drawn bird that echoes the Passerine logo. They acknowledge what each has meant to the other's growth, and Thessaly asks Wren to distribute her wine in the Midwest. The novel ends with them on Thessaly's patio, sharing the last sips, having come through rivalry, partnership, and estrangement to find their way back to friendship, each having built the life she was always meant to lead.