SPOILER WARNING: This article contains spoilers for all episodes of “The Perfect Couple.”

On a quiet summer morning, a body washes up on a Nantucket beach. A scream splits the air –– and a prominent family is immediately thrown into chaos.

So ends the first episode of Netflix’s soap opera drama series “The Perfect Couple,” based on the novel of the same name by bestselling author Elin Hilderbrand. Developed for the screen by showrunner Jenna Lamia (“Good Girls”), the series follows Amelia Sacks (Eve Hewson), whose upcoming nuptials to Benji Winbury (Billy Howle) are disrupted on the day of their wedding when she discovers the dead body of her maid of honor, Merritt Monaco (Meghann Fahy). As police investigate Amelia and her fiancé’s family, they discover that everyone in the bridal party — from Benji’s imposing mother, Greer (Nicole Kidman), to his charismatic best friend, Shooter (Ishaan Khattar) — has been hiding secrets that could destroy the facades they’ve all worked hard to maintain.

The series’ release on Netflix on September 5 marks the culmination of five years of development, during which many changes were made to Hilderbrand’s original novel over the course of time. Variety has compiled a list of the biggest differences between the book and the movie version of “The Perfect Couple” — including that awesome ending.

Featherleigh Dale, meet Isabelle Adjani

In the series, renowned French actor and two-time Oscar nominee Isabelle Adjani plays the cunning, seductive Isabel Nallet, a family friend of the Winburys and, perhaps most importantly, the lover of Thomas (Jack Reynor), the eldest son.

Isabel, however, does not exist in the book –– although the model for her personality, however marginal, may be found in the character of one Featherleigh Dale. In Hilderbrand’s novel, Featherleigh is a British interloper whose financial problems and wanton selfishness put a damper on the weekend’s festivities. Like Isabel, Featherleigh is having an affair with Thomas; unlike Isabel, Featherleigh is something of a hopeless case, though she plays a crucial role in the way the book reveals who murdered Merritt (more on that later).

Greer’s legacy is deeply rooted

Matriarch Greer Winbury –– impeccably played by Nicole Kidman in another role as a struggling wealthy white woman –– bears many similarities to the book’s Greer. Both versions of the character are murder mystery novelists, though Kidman’s Greer is a successful author who has somehow convinced her publisher to throw an expensive-looking party in honor of her new book (though perhaps she paid for it herself?), and Greer in the book is struggling to revive her dying series. Both characters find their strength in calm, preferring to remain aloof and reserved in their interactions with other people. But the series finale of “The Perfect Couple” portrays a Greer not revealed in the book. In a climactic scene midway through the finale, Greer unleashes what may be years of pent-up anger and frustration by revealing to her adult children that she actually met her husband, Tag (Liev Schreiber), while she was an escort. On top of that shocking announcement, the man who keeps calling her throughout the series –– the one the police say has ties to the Turkish mafia (???) –– is actually her brother, Broderick Graham (Tommy Flanagan). Greer’s entire backstory as revealed in the series, as well as Broderick’s existence, is not included in the book at all.

Amelia’s parents play a much smaller role in the series

While we get glimpses of the bride’s relationship with her parents on the show, Celeste’s parents, Karen (Dendrie Taylor) and Bruce (Michael McGrady), are given much more space in the novel. Bruce, a salesperson who has worked in a department store his entire life, drunkenly confides to Tag that he never cheated on Karen, but that he briefly had intense feelings for a former coworker, Robin. Karen overhears and is dismayed: although Bruce characterizes Robin as a woman to Tag, she knows that Robin is in fact a man. The scene has no real bearing on the murder mystery itself, as it serves primarily to deepen the relationship dynamic between Karen and Bruce, which is perhaps why it was cut for the screen.

Tag is a stoner

In the series, Tag keeps getting caught up. In the book, it’s unclear whether he knows what weed is.

The End, Explained

In the series finale of “The Perfect Couple,” it’s revealed that Thomas’ pregnant wife Abigail (Dakota Fanning) deliberately slipped one of Karen’s barbiturate pills into a glass of orange juice and delivered it to a heartbroken Merritt, who is sitting on the beach. After Merritt drinks the juice, Abigail suggests the two go into the water, where she holds the bridesmaid’s head underwater until she drowns. Abigail’s motive is money: she and Thomas are in debt, and he would have had access to his trust once their youngest son, Will (Sam Nivola), turned 18. Merritt’s affair with Tag and subsequent pregnancy threw a spanner in the works: if she had given birth, the clock on Thomas’ trust would have restarted when the baby was born, and they would have had to wait until that child was 18 before they could access the money. Too long, Abigail decided. Hence: murder.

In the book, the drowning is officially ruled an accident by the police and there is no direct killer. Greer is the only one to solve the mystery and she keeps it to herself. Abigail discovers Thomas’s infidelity and slips a pill into Featherleigh’s drink, hoping to put her to sleep so she can’t fool around with Abigail’s husband. However, Featherleigh takes the drink to Merritt. Merritt drinks it and complains to the family friend, who then leaves her to go inside. The bridesmaid wanders the beach, musing on her affair with Tag, and then accidentally cuts her foot on a glass. She wanders into the water to wash it off, sees something shiny at the bottom and realizes it is the ring Tag gave her, so she dives in, gets sleepy and drowns.

Fast forward

At the very end of the series finale, “The Perfect Couple” flashes forward six months, revealing that Amelia is now working at a zoo in London. While she’s showing some penguins to some kids, Greer approaches her.

“I wrote something. Something new,” she says, handing over a manuscript of a new book she says is about Amelia. The two have a heartfelt conversation in the middle of the penguin enclosure, during which Greer admits that she used to hate Amelia, but doesn’t anymore; in fact, she now hopes the two can be friends. The title of the new book? “Your Move.”

This scene isn’t in the book –– which ends with Merritt drowning, told from her perspective –– and it’s perhaps an attempt to introduce a metafictional element to the series: the circle of serendipity of a murder-mystery writer writing about her own real-life murder mystery. While we can’t be sure whether Amelia accepts the olive branch, the joy of the show’s closing dance sequence –– in which the director, Susanne Bier, twirls with the characters –– perhaps suggests that viewers can come away with a sense of resolution that exists, if not on the shores of Nantucket, then in the glory of some other realm.