If Fifi was second-guessing her decision to go alone, she stops doing so the instant she checks into Fifteen Beacon, orders up some room service, and draws herself a bath. Because she grew up with so little, five-star hotel rooms still strike her as an unfathomable luxury—the delicious linens, the fine, heavy pens and creamy stationery, the waffled robes hanging in the closet. Here at Fifteen Beacon, Fifi’s room has a gas fireplace and two deep leather chairs. Someone has sent up a fruit and cheese plate—the front-desk clerk, Pamela, it turns out! She’s a big fan of Shimmy Shimmy.

The greatest luxury of the room is the solitude. Fifi pulls out her manuscript and starts revising. She works until five minutes before she has to leave, at which point she slips her dress over her head and goes down to the lobby. A car is waiting to take her to the Brattle Theatre.

Long relationships have peaks and valleys, and Fifi has every right to some time to herself. What happens next, however, is more difficult to explain.

The day after she speaks at the Brattle is a beautiful spring day. Fifi can shop on Newbury Street, stroll through the Public Garden, even sit on the rooftop at Fifteen Beacon and continue her revisions. But instead, she calls the car service and asks to be delivered to the ferry dock in Hyannis. She’s going to Nantucket.

She calls Mallory in advance (she’s impulsive but not rude) and catches her between her first and second classes.

Thinking about coming to the island overnight; I can probably make it in time for your last class if you’d like me to stop in?

Are you kidding me? Mallory says. My last class is my senior creative-writing seminar. We read Shimmy Shimmy last month. The kids devoured it. I told them we were friends but I don’t think they believed me.

We’ll show them, Fifi says. I’m on my way.

Fifi won’t tell Leland about her change of plans. She knows she should…but she doesn’t want to deal with the inevitable static. Mallory is my friend, not your friend. (Oh, but who is the person who insists they share everything—the apartment, the parking spot in the Bleecker Street garage, the Peugeot that occupies that parking spot? Yes, that’s right, Leland.) Fifi wants to go to Nantucket and see Mallory on her own terms. But why? Is she doing it to piss Leland off?

That may be part of it.

But there’s something else as well. Fifi likes Mallory. She’s smart and fun and…normal. She’s Leland minus the drama. She’s pleasant to look at, though her beauty is quiet, natural—the golden tan, the sun-bleached hair, the ocean-colored eyes. Fifi’s writerly instincts tell her that with Mallory, still waters run deep. Something is going on with her, maybe. Or maybe not.

Fifi and Leland visited Mallory the summer before. They stayed at the Wauwinet Inn for the sake of everyone’s privacy but they had dinner at Mallory’s cottage. The little boy, her son, was spending time with his father in Vermont, so Mallory had the carefree attitude of a teenager whose parents were away. After dinner, Mallory took Fifi and Leland to the piano bar at the Club Car. It was a cramped, narrow, dimly lit space filled with joyful people singing their drunken little hearts out. Mallory knew Brian, the piano player; she sat down next to him on the bench and turned the pages of his sheet music while everyone gathered around to sing “Hotel California” and “Sweet Caroline,” then threw money into a glass jar. Leland had the nicest voice of the three of them but she was the one who had wanted to leave. It was as Fifi followed an impatient Leland out of the Club Car that she’d thought, This would be much more fun without her.

So, now.

Fifi spends less than twenty-four hours on Nantucket, but her time there is transformative for two reasons. The first is Mallory’s creative-writing seminar. Fifi and Mallory arrive at the door of the classroom seconds after the bell has rung; the twelve kids are already seated in a circle and have their notebooks out. Fifi peeks at them through the window.

Mallory swings the door open and says, “You guys, I have a surprise. Fiella Roget has come by to say hello.”

The kids’ heads snap up. Fifi enters the class with just a wave, and she can see the kids puzzling. Is it really her? Then: It’s really her. It’s really her! They start to clap and then one of them stands and then they’re all standing and clapping, a twelve-person standing ovation, and Fifi, who has been applauded and feted and praised all across the country, feels her eyes well up with tears.

There are nine girls and three boys. It’s funny to Fifi how girls dominate creative-writing classes but men dominate the bestseller lists…but don’t get her started. There are five people of color, which surprises Fifi. Nantucket Island; she would have thought that all the kids would be lily-white, privileged, and entitled. But Fifi learns that Nantucket has quite a diverse year-round population; the school’s e-mails, Mallory says, come out in six languages. The kids in Mallory’s class are growing up on an island, like Fifi did, some of them as eager to escape as Fifi was. It’s no wonder they liked Shimmy Shimmy.

It’s obvious that the kids adore Mallory. They call her Miss Bless and they kid with her and tease her, though respectfully. She is that English teacher, the one Fifi wished she’d had in secondary school—the one who listens, the one who reads her students’ work carefully and asks questions without prying, the one who presses a novel into a student’s hands and says, I thought of you when I read this. Let me know if you like it.

Fifi wishes Leland were with her just so she could see this. Fifi and Leland live in a rarefied literary stratosphere where they believe they’re creating culture and influencing public opinion, but the person who’s actually making a difference is Mallory.

The second thing that blows Fifi away is Mallory’s son, Link. He’s four years old, a towhead, a beautiful child with sweet, smooth cheeks and Mallory’s eyes—are they blue? Are they green? Fifi’s experience with children this age is nonexistent; she might as well be meeting a lemur. Link studies Fifi’s face, touches the skin on the back of her hand. He likes her name, Fifi; it makes him laugh. He says it over and over again in his high, clear little voice.

Mallory says, “Your auntie Fifi is a writer. She writes books.”

She tries to write books, Fifi thinks.

Link hears books and brings a stack over to the sofa for Fifi to read to him. How Do Dinosaurs Say Good Night? Bear Snores On. Toot and Puddle. Link points to the pictures he likes and explains them—Toot isn’t wearing pants but that’s okay because he’s a pig—and in some places, he reads along. He’s smart—indeed precocious!

Mallory feeds him small bowls of pasta and edamame, then she gives him a bath; Fifi can hear him splashing and laughing. He comes out to the living room in blue pajamas printed with trains. His blond hair is wet and combed and he smells like toothpaste.

He takes Fifi’s hand and tugs. Mallory pokes her head out of the bedroom. “He wants you to tuck him in,” she says.

This feels like a greater honor than winning the Pulitzer Prize. “Of course,” Fifi says. She hears her cell phone buzzing—Leland—and she thinks about answering it and stepping outside to confess her treachery. I’m on Nantucket with Mallory. But instead, she turns her phone off. She has more important things to do.