The novel begins on the eve of its main character’s graduation from college, where she’s majored in environmental studies. Due to financial constraints, Elise has not been back home to Nantucket since she left for North Carolina four years ago. She’s excited that her mother, Gilda, and her 18-year-old sister, Sophie, are coming to celebrate this milestone with her.

But after a night of partying on campus with her wealthy best friend, Elise awakens to alarming news from her sister: Their mother has gone missing. She never showed up for the ferry, the first stage of their long trip to Chapel Hill.

Gilda, who left Brazil more than two decades earlier, is a cook who puts in 70-hour weeks during Nantucket’s high season in order to support her two American-born daughters. The girls’ father, an Irish bartender whom Gilda met soon after her arrival on Nantucket, headed back to Ireland without a trace when the girls were young.

We soon learn that Gilda, who’d let her last visa lapse 18 years earlier during her rough second pregnancy, was intercepted on her way to the Hyannis ferry by ICE agents and deported, “subject to expedited removal.” An ICE official, it turns out, had been monitoring Gilda’s social media accounts, which tipped the agency off about her plans to leave the island in order to attend her daughter’s college graduation.

Gilda lands back in Brazil at her half-sister’s home, shaken and worried about her daughters. The girls field her frantic calls, often en route to their low-wage summer jobs. Whatever else one might say about Gilda, she has clearly done a good job raising her two daughters, who are excellent students and diligent workers. Sophie, just out of high school, takes on extra shifts at a local upscale café, where she remains unflappable in the face of demanding customers’ complicated orders for fancy coffees. Elise returns to her pre-college summer job monitoring endangered wildlife on a remote stretch of protected shoreline. Fledging plovers become a lovely symbol for how the resourceful women in this family take flight.

When Elise’s college friend Sheba arrives at the summer estate that her two high-powered, socially connected moms have recently inherited from her grandfather, it at first feels like an answered prayer to the sisters’ mounting housing worries.

In an interview with her publisher, Burnham spoke of her firsthand knowledge of housing insecurity on this island of multimillion dollar mansions that sit empty for most of the year: When she was in high school, her family was evicted from their rental home, and she and her sister were placed in foster care. Her mother, like Gilda, was from Brazil and worked in Nantucket kitchens, though she was not deported. Burnham’s familiarity with Brazil enriches both Wait and her first novel, It Is Wood, It Is Stone, about an anxious American woman’s relationship with her grounded Brazilian housekeeper when she moves to Sao Paulo for her husband’s job.

Set during a uniquely stressful summer for Gilda and her daughters, Wait highlights the strong bonds between the three of them. Burnham also probes various friendships, as well as relationships between summer residents and year-rounders on the island.

In contrast to the sisters, Sheba is a woefully unsympathetic character. Her role in the novel is to drive home the familiar point that material riches can be spiritually impoverishing and that financial security doesn’t protect against emotional insecurity. Sheba’s jealousy of Elise’s relationship with Sophie and her petulant sense of entitlement provide too sharp a contrast to the sisters’ caring connection and purposeful lives. It strains credulity that sensible Elise would be drawn to her for so long. Would she be if Sheba weren’t so rich? “Promise you love me for more my than my house?” Sheba says pathetically after she has behaved particularly obnoxiously.

Burnham’s assured narrative pulls us along, although some peculiar word choices give pause: “a cascade of pasta,” “the accomplishment” of Sheba’s mothers’ room, “a stroll of emotion loitering inside her.”

Yet, quibbles aside, Wait movingly tackles serious issues in one of America’s premier vacation spots. It is a commendable accomplishment.