The Perfect Couple Ending Explained: Who Killed Merritt Monaco?

This article contains spoilers for Netflix’s The Perfect Couple.

Throughout the six episodes of Netflix limited series The Perfect Couple, the cops suspect almost every single person in the Winbury’s Nantucket homestead for murder … except one. 

Based on Elin Hilderbrand’s best-selling novel, The Perfect Couple plays out like a whirlwind beach read. The all-at-once drop on Netflix allows viewers to watch it much like they would devour one of Hilderbrand’s books in real life, with uninterrupted gusto, insatiable curiosity, and lots of schadenfreude for the affluent characters at the center of the action. Much like The White Lotus or Big Little Lies, The Perfect Couple centers on a murder in the midst of the physical comforts and psychological dysfunction that can come with unimaginable wealth. 

There are some familiar faces from those two shows as well. Nicole Kidman, familiar from oh-so-many things, but also a pivotal character from Big Little Lies, plays Greer Garrison Winbury, a world-famous romance novelist who churns out paperbacks faster than her rabid fans can read them. Meghann Fahy from The White Lotus plays the victim, the Instagram-famous party girl Merritt Monaco who has traveled to the Winbury home for her bestie Amelia’s wedding, only to end up drowned in the ocean on the evening of the rehearsal dinner. 

Who killed Merritt? And why?! The show cycles through all the obvious — and not-so-obvious — suspects in the first five episodes, only to drop some absolutely wild bombshells in the final chapter. Let’s break it down, juicy secret by juicy secret, and get to the bottom of this whole thing. 

Greer’s Secret Brother And Even More Secret Past

As the final episode begins, Greer’s husband Tag (Liev Schreiber) has just gone on a drunken rant at her most recent book launch. You see, they’re not the most perfect couple after all. Mostly because Tag cheats on her all the time and has gotten multiple women pregnant, including Merritt, but he’s no killer. He’s pissed at Greer for attempting to frame him for Merritt’s murder, and once he gives the cops the information from his Fitbit type-device, it shows that he was snoozing in bed at the time Merritt died, but the second sleeper was awake. 

The cops bring Greer in for questioning, and put together that she was on the phone with a seedy dude named Broderick Graham at 3:08 am, or the approximate time of Merritt’s death. Furthermore, they found a wire from Scooter Dival (Ishaan Khattar) to Broderick for $300,000. They assume that Greer used Scooter to pay a hit man to have her husband’s lover killed, but what they don’t know is that Broderick is her brother. Gasp! 

This begins the most wild and out-of-left field string of bombshell revelations in the entire series. Greer has been supporting her deadbeat brother for years. Okay, that’s not that salacious, but the existence of a secret brother seems to come out of absolutely nowhere. The daytime soap vibes are strong, and I say that with the highest of compliments. Then! When Greer comes back home, she unleashes a breathless, bug-eyed tirade about the capital-T Truth of her and Tag’s relationship. They were never the “perfect couple.” You see, Broderick was also Greer’s john when she was young, and she was a highly paid escort. Tag was a client who was so smitten with her that he ended up locking her down for life. And, in an ironic twist of fate, Greer ended up paying for everything with her hard work all along. 

The Pentobarbital Red Herring

Now, why would Greer have to pay for everything if the Winbury family is literally made of money? Well, there’s a trust you see, and the trust doesn’t release until all of the Winbury children — presumably all of Tag’s offspring — turn eighteen. It feels weird that Tag wouldn’t have his money until his kids came of age, but I guess that trusts can be set up in all sorts of crazy ways? I don’t know. Most of us will never have to actually know how trusts work, so let’s just play along. 

The Winbury kids are scandalized by this reveal about their mom, but there’s still a killer on the loose. Ameila’s mom chooses this moment to pull her own reveal, namely that she had three pills of pentobarbital in her medicine bag for emergency self-euthanasia purposes in case the pain related to her cancer became unbearable on the trip. This is obviously a very sad twist in the narrative, but The Perfect Couple doesn’t dwell on the tragedy of it all. Instead, the show flips to the douchiest of the Winbury sons, Thomas (Jack Reynor), as we get to see the shenanigans he got up to on the day of the rehearsal dinner. Thomas often stole pills from other people in a prep school game he called “prescription roulette,” so when he nabbed a pill from Amelia’s mom, he thought it was an oxy, not a potential harbinger of death. 

We already knew that Thomas was an absolute waste of space — he’s cheating on his pregnant wife with his dad’s old French lover AND he’s borrowed millions of dollars from her to boot — but the fact that he’d steal pills from a dying woman is a bridge too far. He doesn’t end up being the killer, but we should probably just throw away the whole man, just to be safe.

Thomas does reveal something that’s only been hinted at throughout the rest of the series, though. The Winbury trust doesn’t disperse until Will (Sam Nivola), the youngest, comes of age in a few weeks. If Merritt and her unborn child had lived, that would have pushed back the release another eighteen years. Yikes. He leads the cops to his mistress, Isabel (Isabelle Adjani), never once suspecting that his wife, Abby (Dakota Fanning), may have had something to do with the murder. 

Who Really Killed Merritt Monaco?

Literally no one suspects Abby throughout the entire show. Viewers may have picked up on clues, such as her frantically washing a glass in the second episode when it’s crystal clear that Abby never lifts a damn finger to do any other household tasks. Or her preference for yellow dresses may have tipped people off before the big reveal. Nevertheless, she’s the very last person the cops haven’t questioned, and Detective Karen unearths a true “Karen” when she realizes that Abby lied to her about Thomas coming to bed on the night of the murder. Abby lies to her yet again when she picks her husband up from the police station, and a lightbulb goes off over the good detective’s head. 

A pregnant Abby was also waiting for the trust to release so that she could live the moneyed life she’d always dreamed about, one where she could wear vintage all the time and freely travel to countries with lax face cream regulations. She, too, realized that Merritt’s baby would delay the Scrooge McDuck windfall that was about to come her way, and she wasn’t staying with her philandering, asshole husband just for kicks. So, she took matters into her own hands. 

She found the mystery pill in Thomas’s stash, ground it up, and offered it up in a glass of orange juice to a distressed Merritt as she despaired on the beach into the night. Merritt accepted the offer, drank the poison (which may have been enough to terminate her pregnancy without killing her, but hey, hindsight is 20/20), and then dazedly followed Abby into the ocean for a swim. The pill incapacitated Merritt enough so that the very pregnant Abby was able to easily drown her in the shallow water. How she ever thought she was going to get away with it sort of makes sense because there were plenty of other suspects, but also what were you thinking, girl? Maybe she was thinking she’d rather go to jail than live a life with no money? 

The case is shut, but there’s one final, perhaps unintentional, mystery that the series poses as the final scenes unfold. We find out that Greer finally leaves Tag and goes to write a new book. Amelia (Eve Hewson) has also broken off her engagement with Greer’s son Benji (Billy Howle) and is now working at the London Zoo. Greer finds her, all smiles, and wants to be friends. Instead of writing a book about her own, fascinating life, she’s written about Amelia for some reason? And she wants to be besties with her son’s ex fiancee? It’s a perplexing end to a fun romp of a show that brought an entitled brat to justice and exposed all of the other Winbury brats along the way. What a way to end brat summer. 

All six episodes of The Perfect Couple are available to stream on Netflix now.