In Venice, 60-year-old American painter Robert Noonan reviews a packet inviting him to join the faculty of Columbia University’s Master of Fine Arts program in painting. The packet includes an apology from critic Irwin Popov, who teaches in the program and once savaged Robert’s work. Back at his Giudecca studio, Robert’s art dealer, Hugh, finds an unfinished self-portrait on the easel and derides it as “all worm,” his term for Robert’s habit of focusing on the unpleasant aspects of life. The image of Robert includes a birthmark that Robert doesn’t have. In the portrait, a painting of the Bridge of Sighs hangs on the wall behind the subject, so obscured by shadow that Hugh interprets it as a gallows. Hugh inspects the work for an upcoming New York show and says it will sell despite his reservations, while griping about the studio’s cost and Robert’s debts to ex-wives.

Over dinner at Harry’s Bar, Hugh and Robert talk about another expatriate painter in Venice, Anne Brettany. Hugh mentions that Anne still loves Robert and feels overshadowed by him artistically. He urges Robert to come to New York to promote his work. He confronts Robert about his recent reclusiveness and about the depressive quality of his new work. Robert threatens to punch him; Hugh offers his chin, tearfully urging him to be provocative again.

Robert confesses that he’s afraid of many small things, though not death; it’s his recurring bouts of overwhelming grief that frighten him. Back in the studio, he finally acknowledges that the portrait’s real subject is his father. His lover, Evangeline Lichtner, arrives unexpectedly.

The Lynches buy a house on Third Street in the East End. Big Lou is elated by homeownership; Tessa, anxious about money, reminds him that the middle class can slip down as easily as up. Next door, Edith and Janet Spinnarkle—described as “spinster” sisters—live downstairs, and the Marconis, who moved to the East End a year earlier, rent the upstairs flat.

Tessa makes Big Lou promise not to feud with Mr. Marconi, but the rivalry lingers. Both men are route workers: Big Lou delivers milk in the Borough; Mr. Marconi delivers mail in the West End’s Gut. When Mr. Marconi buys a station wagon, Big Lou’s curiosity spikes. His attempts at neighborly conversation are rebuffed. Tessa and Mrs. Marconi maintain a quiet friendship, and Tessa learns troubling details about the Marconi household.

Upon Mr. Marconi’s promotion, the family plans to move to the Borough. To soften the blow, Lucy’s parents give him an expensive bicycle. Exploring Thomaston, he befriends Gabriel Mock, Junior, the caretaker at abandoned Whitcombe Hall, who calls him Junior. Junior warns him about underground caves.

On Saturdays, Lucy and Bobby “surf” Big Lou’s milk truck, standing in back as it corners. Mr. Marconi warns Big Lou that he’ll be responsible if Bobby is hurt. The game continues. Jealous of Bobby’s fearlessness, Lucy fails to call a turn; Bobby is thrown and breaks his wrist, and he blames Lucy.

Mr. Marconi publicly humiliates Big Lou by refusing Big Lou’s offer to pay the hospital bill. Lucy confesses to Tessa that he failed to call the turn. She in turn implies that Bobby took part in the trestle incident, which Lucy denies.

After the Marconis move to the Borough, Lucy’s trance-like “spells” return. Big Lou drives him through the Borough, insisting that he belongs anywhere in town and urging him to choose friends who reciprocate. Big Lou notes that the Marconis likely kept their old number. That night, Lucy calls; Bobby answers, but Lucy hangs up when Mr. Marconi takes the phone.

In the present, in Venice, Evangeline wakes Robert from sleep and tells him that he’s been talking, repeatedly apologizing. They have not spent the night together since Robert, during a night terror a month earlier, accidentally punched her and left a black eye that she struggled to explain to her husband.

Robert walks Evangeline home. At her Campo San Stefano gallery, she laments her failing business and stagnant life. She says she wants to end their affair but asks him to accompany Hugh to the gallery the next day. After she enters the building, Robert lingers.

Evangeline’s husband, Todd Lichtner, ambushes Robert, punching him hard in the chest with a roll of quarters that bursts on impact, scattering coins. They get drinks in a student bar at Campo Santa Margherita. Todd admits his own infidelities but insists he doesn’t sleep with friends’ wives. Robert suggests divorce; Todd refuses, saying they’ve weathered worse. He apologizes for the punch and asks to sleep on Robert’s sofa, since he isn’t supposed to be back in Venice until morning. Robert agrees to leave his door unlocked.

In the present, in Thomaston, Lucy watches his son, Owen, fill water jugs from their spigot. Owen and his wife, Brindy, can’t drink the water from their own well because it is contaminated with arsenic. They bought the house hastily, without inspections, Lucy wonders if Brindy’s pregnancy loss last winter had anything to do with the contaminated water. These thoughts prompt him to remember his father’s pride in their first East End home and the mid-century American optimism that came with it.

Inside, Owen asks about the memoir and Bobby Marconi. He says Sarah told him Bobby supposedly almost killed his own father.

The narrative returns to Lucy’s childhood, as a new A&P supermarket threatens local businesses. Big Lou’s dairy is sold, his route shrinks, and his job security vanishes. He spends afternoons at the Cayoga Diner with unemployed men, staying optimistic despite warning signs, while his brother, Declan, taunts him.

Tessa and Big Lou argue over keeping Lucy at St. Francis, really about Big Lou’s job. Big Lou begins spending time at Ikey Lubin’s corner market, known for illegal bookmaking; Tessa suspects he’s gambling and is furious.

Lucy keeps visiting Gabriel Mock Jr. at Whitcombe Hall. His mother recounts how, when she and Gabriel were both preteens, he once kissed Tessa on a public street after she was kind to his dying sister, Kaylene Mock. Because Gabriel is Black, this gesture could have exposed him to racist violence. His father beat him to protect him.

Lucy returns to find his parents fighting. Big Lou has bought Ikey Lubin’s store against Tessa’s wishes. She is enraged and vows never to enter. For months, Tessa swings between rage and depression, while Big Lou is silent. Lucy helps at the store, where he feels safer and has fewer “spells.”

After two months, Tessa presents a detailed plan to turn the corner market into a success by offering greater convenience and longer business hours than the A&P. She gives Big Lou an air gun to deter dogs from urinating on the produce bins and demonstrates its use. That night, Big Lou walks alone into the darkened store; Tessa says he’s seeing it for the first time. Later, Lucy overhears them make a new pact: Tessa will help with the business, and Big Lou promises they will never move into the dilapidated apartment above the store.