Serena was grateful for the time alone. And, she realized, Liza trusted her enough to leave her alone in the boathouse. She was also grateful for that.

She watched Liza and Raj walk toward the water, both without looking back. Liza is handling this well, Serena thought. Like someone who’s old enough to withhold judgment. Serena wandered around the office. The mementos were few, a couple of photos from talks, an official portrait with former president Clinton, a photo of Maeve in what looked to be a wedding dress, no veil, only a spray of roses and baby’s breath woven into her hair.

There were various medals of honor and honorary degrees in a pile. A framed New Yorker cover signed by the artist. Serena noticed there were only a couple of family photos. One was of Liza’s beautiful children, whom she had seen at the wake. In this picture, the twins were tan and happy, on a sailboat. My niece and nephew, thought Serena for the first time, surprised that she hadn’t connected the family dots beyond the three sisters. I have a niece and nephew and a brother-in-law. As an unmarried only child, those kinds of relationships hadn’t even occurred to Serena. Now, she had an extended family. She studied the photo . The boat’s name was Sunkissed, and that’s exactly the way the children looked: sunkissed.

The other photo was the sort of family shot that was mandatory in all holiday cards these days: posed and perfect. Serena wasn’t sure when these sorts of cards had become mandatory holiday missives; she didn’t recall the onslaught occurring in her childhood. Certainly, the Tucker family didn’t

make the posed portrait an annual event. Maybe at her deb ball there was a photo card, or something from that one perfect ski vacation in Sun Valley, but Birdie Tucker favored cards from the Metropolitan Museum of Art that she had engraved and then personalized with a short note. These days, Serena got dozens of cards every year from classmates and colleagues who wanted to advertise their excellent gene pool and tout accomplishments ( Starting pre-K at Sidwell! MVP of the soccer squad! Youngest girl on the Robotics Team! ). Serena tossed them all in a silver bowl by the front door for a few weeks and then tossed them out on January 2. Serena was sure Liza sent out these trophy cards on expensive stock with gold engraving.

Maybe she’d get one next Christmas.

But this Sweeney formal family picture seemed out of character for free-range Maeve and her daughters. Liza and Maggie were tweens and Tricia was about six. All the Sweeney women posed on the lawn of Willow Lane, as if a picnic were about to break out, snuggled close to each other, hugging and laughing. Maeve was in a white sundress with silver bangles on her arm, her hair up in a loose bun, gold sandals on her feet. God, she was gorgeous. The three sisters were in coordinated blue-and-white flowered dresses, all with their long red hair neatly combed and held back in headbands with tiny purple flowers. Serena did the math and thought about those May Day celebrations. This photo was probably Maeve’s last good year, before the diagnosis and the years of treatment, remission, recurrence, and more treatment. The photographer took the photo from above and all their lovely faces were tilted toward the sun.

I was probably sitting in my room, five hundred feet away, listening to the laughter, Serena thought. She looked out the window of the boathouse and saw her childhood home. I was there the whole time.

Enough melancholy. Raj and Liza were at the end of the dock, talking about her, she presumed. Tricia had said she could be on that work call all afternoon. And Maggie had wandered back to the studio, instructing Liza to swing by after the boathouse tour. Serena guessed she had at least a few more minutes.

She went to the six-drawer file cabinet behind the desk, assuming that’s where the personal papers might be held and opened it. She didn’t know quite what she was looking for, but she was sure she’d know it if she saw it.

Her mother had given her one tiny clue in their only conversation: William Sweeney had called her mother Rebecca, her given name. Maybe

somewhere in the office there was a file titled “Rebecca,” which held the answer to the only question Serena really had: Did Bill Sweeney know that he was her father all along?

Liza and Raj walked the length of the dock in silence. The weather was warming up. It would be hot and sticky by the Fourth of July in a few days and then the summer would start in earnest, with American flags flying on every house, lobsters and cocktails on the beach, and fireworks up and down the Connecticut shoreline. If it was a normal year, Liza would be organizing a party at the club for “their crowd,” meaning the couples that passed the test: Does he talk about anything other than work and golf? Does she talk about anything other than the kids? From this bottom line, Liza and Whit had built a group of regulars at parties that included a mix of old Southport, new money art collectors, and a few fun gay couples who summered in town. But not this year. She’d taken the event off her list when her father died, sending out a short email to participants about her decision.

With Whit’s departure, Liza realized she might never host another “Festive Fourth,” as floral designer Anthony had called it every year in his beautifully handwritten thank-you note.

Liza watched a fleet of junior sailors in Bluejays, heading out the mouth of the harbor for a sailing lesson, laughing and shouting boat to boat as their sails picked up more wind in the open water. She imagined Vivi and Fitz at camp, sailing on the pond in Maine. Vivi loved sailing on a lake but was too scared of sharks and sea monsters to sail on the Long Island Sound, like Liza had been when she was young. But the kids out on the boats today had no such fears. Their enthusiasm made Liza smile. Freedom.

It was Tricia who had been the sailor in the Sweeney family, attracted to the rigor and discipline of the sport. Liza and Maggie were interested in sailing instructors, but not sailing. When they were teenagers, they would sit on the end of the dock in their bikinis and wait for the cute sailing instructors, from Brown or Hobart, to motor by in their Boston Whalers. We wasted a lot of time on boys, Liza thought as she and Raj reached the end of the dock. We should have learned to sail.

“I know this is none of my business, but that woman had a very strong reaction to your father’s office. Is that normal?”

“Do you know who that is? Serena Tucker. Is that name familiar?”

“The name’s not familiar. Should I know her?”

“She’s a journalist. Washington Post. Slate. Straight Up.”

“Tricia said that, but she didn’t say ‘cousin.’ Did they have a falling out?”

“You signed that NDA, right?”

“I did.”

“Well, then, here you go.” Liza made the split-second decision to tell Raj.

“Yes, she’s a journalist, but not our cousin. Here comes the NDA bit: we recently learned that she’s our half-sister and Tricia is freaked out by it all.”

That felt so good. Liza had been on the verge of exploding since Whit had packed his bags and headed back to North Carolina with everything he could jam into the back of the Cayenne, from his golf clubs to the top-of-the-line one-touch espresso maker. Telling Raj about Serena put her back in balance. One secret was enough to keep. Two was killing her.

Raj was the perfect confessor—a sensible neutral party new to the neighborhood, slightly in awe of her father’s legacy and silenced by a nondisclosure agreement. Given enough time and wine, Liza might tell him every secret she’s ever held, from her one truly wild night with the lead singer of the Goo Goo Dolls in 2002 to the time last New Year’s Eve when she and Whit stole a bottle of champagne off a room service tray on Necker Island. Liza, who felt like she’d been hiding in her own life for a decade, was now having trouble staying quiet.

She needed to confide in someone about something, and Raj was standing right next to her, legally barred from repeating anything she said.

The perfect stranger. “Our father had an affair in the early 1980s and Serena is the product of that affair. The affair was with the mom next door, which is . . . disappointing. So, Serena grew up across the street from us, but we didn’t know her well because she’s slightly older than me and her parents were super snobby. I’m sure my mother wasn’t good enough for them and I have no doubt that Mr. Tucker thought my father was a drunk, no-talent communist from the way he waved from his driveway but never once attempted conversation with our family. But we learned the truth last week.

There is a fourth Sweeney sister.”