Beach Reads and Deadly Deeds

In the prologue, Diana Harden, a 32-year-old woman from New Orleans, returns to St. Claire, a private Caribbean island resort, after a frustrating trip to the neighboring island of St. John. She goes to the private dock of Ethan Valentine, the reclusive billionaire who owns the island, intending to sell him stolen documents at a steep price. An elderly man on the deck tells her Valentine is not home. Diana treks back toward the resort, mentally cataloguing the guests and staff she plans to blackmail. When she reaches her cottage, someone she recognizes grabs her from behind and strangles her with her own scarf.

The story shifts to the first-person narration of Mia Crawford, a nearly 30-year-old CPA and financial planner from New Jersey. A devoted reader who never travels without a book, Mia is heading to St. Claire because her boss at McMann & Cohn Financial Planners insisted the trip serve as her five-year anniversary bonus. A promotion to full partner awaits her return, but the permanence of the commitment unsettles her. On the ferry, she meets several guests, including Amber Jones, an aloof redheaded actress, and David and his husband Doug, who are celebrating their anniversary. David and Doug mention that a woman named Diana Harden went missing from the island two days earlier.

At the resort, Mia is immediately attracted to a handsome man in the lobby who turns out to be Jason Mallory, the head bartender and daredevil hang glider. In the gift shop, she picks up a tattered romantic thriller left behind by a previous guest. Reading on the beach, she discovers that someone has written extensively in the margins, tracking guests' net worth, recording cryptic numbers, and speculating about secrets people would pay to keep hidden. A business card from a New Orleans antiques shop serves as a bookmark. Mia suspects the book belonged to Diana and that Diana was blackmailing people on the island. She also overhears Amber arguing with a man who threatens her about missing documents.

Mia meets more guests over the following days. CeeCee Tremaine is a bubbly young woman whose much older boyfriend, Trevor Lance, turns out to be married. Andrew Locke is a retired baseball player vacationing with his 18-year-old daughter Brie and his girlfriend Sherry Morrison. Parker Briggs, Amber's ex-boyfriend, is the man Mia heard threatening Amber. At the bar, Mia and Jason flirt, and he challenges her cautious worldview. She bonds with Brie, who proves to be a sharp internet researcher. Together they uncover that Amber and Diana were romantically involved and that Gino Garmon, the resort's head of security and a former Miami police officer, resigned under suspicion of skimming money from drug busts. Mia cracks Diana's number code, in which each person is assigned a number based on their initials' positions in the alphabet.

The mystery deepens when Diana's body washes ashore with a scarf wound tightly around her neck. Gino takes charge of the investigation, though Mia distrusts him because of his exposed misconduct and his aggressive interrogation of her. The resort manager, Tristan Dubois, assures Mia the St. John police are involved.

Mia and Jason grow closer. At a hidden lagoon one evening, Mia confesses her secret dream of owning a bookstore, a fantasy she has always dismissed as irresponsible. Jason encourages her, and their emotional connection deepens. Meanwhile, Mia's investigation intensifies. She travels to St. John, where a teenage boat operator admits he brought Diana back to St. Claire on Sunday evening, dropping her at Ethan Valentine's dock. This contradicts the official narrative that Diana disappeared on St. John. Mia also follows Sherry and witnesses her handing cash to a suspicious man. That night, someone breaks into Mia's cottage and steals the book. Brie, who had secretly photographed every annotated page, preserves the evidence. When Mia and Brie later follow Amber and Parker up a mountain trail to watch them search for Diana's hidden documents, Mia falls into a deep construction pit and is trapped until Brie brings help. Gino privately threatens Mia, warning her to stay out of his investigation.

Jason plans an elaborate belated birthday surprise for Mia: a Jet Ski ride, a hidden cavern with a waterfall, and dinner on a boat anchored offshore. When someone sabotages both vehicles and strands them overnight, they make the best of it. Mia tells Jason everything she knows about Diana's blackmail schemes, and they make love for the first time under the stars.

Events accelerate when Gino is found dead on the rocks near the dock. Tristan announces that a young staff member named Georgie Arendt is the suspect, but Jason tells Mia privately that Georgie tore a page from the book on Gino's orders and is hiding out of fear, not guilt.

Brie learns that Andrew plans to marry Sherry the next evening. Mia and Brie visit Amber, who possesses a video in which Sherry drunkenly describes her strategy of serially marrying wealthy athletes, naming Andrew as a future target. While Mia distracts Amber, Brie copies the video. Mia also retrieves Diana's phone from Gino's locked desk. At the Sky Bar ceremony, Brie arrives bruised and soaking wet, having escaped the man Sherry hired by jumping overboard, and plays the video through the ceremony microphone. Andrew calls off the wedding.

Mia also deciphers Diana's final code. Five numbers on the torn page correspond to page numbers in the novel, each pointing to a circled word that represents an author's surname. These clues lead her to the resort's library, where she finds documents hidden inside a copy of The Girl with the Dragon Tattoo. The papers prove that Parker stole intellectual property from Ethan Valentine three years earlier, precipitating Valentine's retreat to St. Claire.

At the party, Mia hands the documents to Tristan and announces that Ethan Valentine would want them. Parker lunges for the papers, causing chaos. Mia realizes that Tristan inadvertently revealed knowledge he could only possess if he had seen Diana the night she died. When confronted, Tristan panics and addresses Jason as "Ethan." Jason is Ethan Valentine, the reclusive billionaire who has been living anonymously as the resort bartender for three years. Luis, a cigar-smoking elderly man who lives on the island and is rumored to be Ethan's great-uncle, is among the few aware of his true identity. Tristan flees, and Ethan chases him to a zip line platform above the lake. Tristan kicks Ethan off the edge, but Ethan grabs the trolley handle and zip-lines partway across before falling into the water. Mia, conquering her fear of heights, follows on the last trolley. On the far shore, Tristan confesses: He killed Diana because she discovered Jason's true identity and threatened to expose him, and he killed Gino because Gino deduced Tristan was the murderer and tried to blackmail him.

Mia is devastated. She tells Ethan she fell in love with Jason Mallory, a person who does not exist. Despite his pleas, she walks away. As the ferry pulls away from St. Claire two days later, she sees Ethan sitting alone on a Jet Ski in the open ocean. He blows her a kiss. She catches it, then faces forward.

Six months later, Mia has declined the partnership and opened Beach Reads and Mysteries, a bookstore in Miami, complete with cozy nooks, a café, and thousands of tiny white lights. Ethan walks in, tells her he loves her, and reveals he has opened an office in Miami. Mia realizes she loves him, that Jason and Ethan are the same person where it counts, and kisses him.