That night, as Kacy is trying to sleep, her phone dings with a text from Isla.

I miss you, Bun.

Kacy runs her fingers over the words. Bun is short for honeybun—honey refers to the color of Kacy’s hair. She wonders how things are going in the NICU, who the new babies are, how people like the nurse they hired to replace Kacy, if Isla has been acting sad and distant and, if yes, has Rondo noticed?

Another text comes in: I don’t understand why you had to LEAVE. I was going to tell him, I just wanted to do it on my own timeline, not because you were pressuring me.

Kacy considers this. Did she pressure Isla to break the engagement? Maybe, but they were in love. Isla’s relationship with Rondo, as Isla herself said, was a sham. Isla came from a fancy Mexico City family—five-story town house in Condesa, beach home in Tecolutla—and Isla’s mother wanted all the California things for her daughter: UC Berkeley, Stanford School of Medicine, a Napa wedding to a man who was also a doctor, a home in Presidio Heights, three or four children, season tickets to the 49ers, a standing reservation at Gary Danko. Kacy and Isla had countless conversations about how Isla should be living an authentic life—she needed to break things off with Rondo, come out to her parents. “You don’t understand how hard that conversation is going to be,” Isla said. “My parents are traditional Catholics. My mother will faint; my father will schedule an exorcism.”

“They’ll get over it,” Kacy told her.

“You’re right, I know you’re right. I just need more time.”

“You don’t have to tell them about me right away,” Kacy said. “But please, for the love of god, break up with Rondo.”

“I definitely will,” Isla said—but what Kacy has learned is that she definitely won’t.

Another text comes in: Leaving was manipulative. You did it to force my hand.

Isla and Rondo must have had a glass of wine or three in front of their gas-log fire, Kacy thinks.

Then, in a move so cruel Kacy can’t quite fathom it, Isla sends a picture of Kacy holding Little G. The next text says: The unit needs you, Kace. It was selfish of you to leave.

Don’t take the bait, Kacy thinks.

Another text: So that’s it? You’re not going to talk to me? Aren’t you more mature than that?

What could be more mature, Kacy wonders, than choosing not to engage? Besides, it’s ten forty-five, and Kacy wants to go for a run in the morning, then drive Coco out to Great Point.

Another text: I love you, Bun.

I love you too, Kacy thinks. She clicks out of her texts and hops on Instagram, where she sees Rondo’s newest photo, posted that morning. Rondo and Isla are seated at a leather banquette with Dr. Dunne and his wife, Tami, who has enormous breast implants and microbladed brows. Behind them is pink-and-green tropical wallpaper that’s so recognizable, Kacy doesn’t even need to read the caption to know where they are, but she does anyway. Champagne and seafood tower @leosoysterbar with my best man and the always-chic @totally_tami_.

Unfollow Rondo, she thinks. Then go to sleep.

But Rondo’s account is Coco’s only window into Isla’s world. Isla and Rondo went to Leo’s with the Dunnes the night before; afterward, they probably hit the bar at Wayfare for a cocktail. Isla’s texts sound lonely but she’s been double-dating with Dr. and “Totally Tami” Dunne. Kacy wants to hurl her phone across the room. She types, Sorry, I’ve been busy. Then she attaches two pictures: Coco trying on the white sundress and Coco and Kacy at the pharmacy lunch counter, their faces squished together, cheesing. She presses Send.

There’s no immediate response and Kacy chides herself for sending the photos. She’s using the pictures of Coco as a weapon without Coco knowing it, and she’s using them out of context. Her friendship with Coco is brand-new and already she’s compromised it.

A minute or two later, a text comes in: Wow, you work fast.

Just friends, Kacy says, but her spirit is buoyed. Isla is jealous.

As if reading Kacy’s mind, Isla texts, I’m sick with jealousy. Now I won’t sleep. Thanks.

Mission accomplished, Kacy thinks. She turns off her phone and closes her eyes.

8. Thursday, August 22, 8:45 P.M.

On the way from Ventuno to the ashes of the house on 888 Pocomo Road, Ed throws on the lights and sirens; his heart is beating twice as fast as it should, and his thoughts spin out. He needs to calm down—what did Dr. Head Honcho say about stress? He doesn’t want to alarm Kacy with the news that Coco is missing, but Kacy, in the passenger seat, keeps calling Coco over and over again.

“It just goes straight to voice mail,” she says. “What do you think that means?”

Ed thinks, but does not say: If Coco went overboard, her phone probably did too.

Andrea wanted to come to the scene, but Ed asked her to go home with Eric and Avalon. Andrea had been drinking, and unlike him, she’d had a lot more than half a glass of red wine. He needs to breathe—what are his meditation cues? He can’t recall a single one. Why did he succumb to temptation and order the Fiorentina, then eat a cannoli? He has only one hundred hours left on the job… and now this.

His phone rings. It’s Lucy Shields, the Nantucket harbormaster. Thank god. He puts on his headset; he would prefer that Kacy not overhear any of this.

“Lucy.”

“Ed,” she says. “What a mess. A doubleheader like this in your final week.”

“Who have you talked to?”

“Only the captain, Lamont Oakley. He called it in about twenty minutes ago: Guest on Hedonism no longer on the boat. Twenty-seven-year-old female named Colleen Coyle; five foot four inches tall; approximately one hundred and five pounds; dark, chin-length hair; worked for the owners of the boat.”

The Chief clears his throat. “Yes, we know her. She’s friends with our daughter, Kacy.”

“Oh god, Ed, I’m sorry,” Lucy says. “Was Kacy on the boat as well?”

“No, no, she’s here in the car with me.”

“Can she hear us?” Lucy asks.

“Negative,” Ed says, and he hopes this is true.

“That’s probably best,” Lucy says. Lucy Shields has been the harbormaster for a long time. She was Kacy’s boss back when Kacy worked as a town lifeguard in high school. It’s a small island, the Chief thinks.

Lucy says, “It’s unclear if Ms. Coyle had been drinking or what her mental state was during the party. Lamont told me the last time he saw her was as they were passing Eel Point heading east-northeast, so we’ll go with that unless you and your officers find out anything different. Lamont was sailing solo—the Valladares brothers were at their abuela’s birthday—so Lamont would have had his hands full with that boat and all those guests. He seems confident that Ms. Coyle can swim, which is good. The Coast Guard boarded the boat to do a search and they’re bringing everyone ashore for questioning, but they’ll keep them away from the house fire.”

“Are you thinking what I’m thinking?” Ed asks.

“That she was disgruntled? Somehow arranged for the house to catch fire while they were out sailing, then ditched?”

Ed considers what he knows about Coco, which admittedly isn’t much, though he’s seen her a fair amount this summer, both at his own home and whenever the Chief and Andrea went to the Richardsons’. His first impression of Coco when she climbed into the back of his car was that she was a loner, a wayward soul. But she would have made Charles Darwin proud, the way she adapted to Nantucket life. She befriended Kacy; she seemed at home at Triple Eight Pocomo Road. She became as confident and as at ease as any other young woman ordering a mudslide at the Gazebo. Nantucket has a way of getting in your blood; Ed knows this firsthand. He and Andrea and all their friends arrived from elsewhere and now they’re as embedded on the island as the bollards of Old South Wharf.

What do they know for sure? The Richardsons’ house has burned to the ground, and on the same evening, an employee of theirs has gone missing. This feels like more than a coincidence, but if all these years of policing have taught Ed anything, it’s that one should never jump to conclusions.

“Let’s just worry about finding her for now,” Ed says. “You’ve launched a search?”

“I sent one boat from Nantucket Harbor and one from Madaket Harbor,” Lucy says. “I’m waiting on word from the Coast Guard in Woods Hole. If we don’t find her in the next thirty minutes, they’ll send a helicopter from the air station. We’ve authorized a track-line search from Dionis to Smith’s Point, winds are fifteen to seventeen, seas two to four feet, which is good for sailing, bad if you’re trying to swim—and the tide is going out, unfortunately. It would help if you could identify the last person who saw her.”

“I’m almost to the scene,” the Chief says. “I’ll let you know what I find out.”

The instant they turn onto Pocomo Road, Ed smells smoke. Once they reach the Richardsons’ white-shell driveway, he can see a cloud hovering by the water and the smell changes from mildly pleasant campfire to bitter and acrid, then suddenly it’s like he’s driving through fog. Civilian cars line the right side of the Richardsons’ driveway—guests attending the Richardsons’ sail—but there’s enough room for emergency vehicles to get through. The NFD sent Engine 4, Engine 1, and Tanker 1, since there’s only one dry hydrant out here, at the start of Pocomo Road. There’s an ambulance and an NPD squad car as well, probably Dixon’s.

Ed parks and turns to Kacy. “How are you doing?”