[Warning: The below contains MAJOR spoilers for The Perfect Couple.]
When Merritt Monaco’s (Meghann Fahy) body is found floating in the water, all eyes turn to the privileged and seemingly perfect Winburys. The night before, Merritt celebrated the impending wedding of her best friend Amelia Sacks (Eve Hewson) to the blue-blooded Benji Winbury (Billy Howle). Just hours later, she was dead.
Over the course of The Perfect Couple’s six episodes, the suspects changed as more details were revealed about the past and present. Tag (Liev Schreiber) became the prime suspect because of his affair with Merritt and the fact that she was pregnant with his child. The police even believed Greer (Nicole Kidman) could have been responsible at one point.
However, Tag wasn’t the killer. The reason behind Merritt’s murder was much more complicated and sinister than anyone ever thought.
The series finale revealed Abby Winbury (Dakota Fanning) was the killer all along. The pregnant wife of Thomas Winbury (Jack Reynor) took matters into her own hands to protect herself and her husband once she found out a major trust fund game-changer.
The reason? The Winbury sons would receive their trust funds only after the youngest child turned 18. Greer and Tag’s youngest son, Will (Sam Nivola), would celebrate his 18th birthday a few weeks after Amelia and Benji’s wedding. If Merritt had her and Tag’s baby, the trust fund would automatically reset, and Thomas, Benji, and Will would have to wait another 18 years to get their cash.
After questioning Thomas, Detective Henry (Donna Lynne Champlin) started to put the pieces together. She rewatched the footage of her interview with Gosia (Irina Dubova), the Winbury maid. Gosia complained about Abby’s constant demands, most notably the one she made after Merritt’s death. Abby ordered Gosia to wash her water glass, but she didn’t. When Detective Henry first arrived on the scene, she found Abby washing the glass, the one Merritt drank from the night she died.
Detective Henry confirmed her suspicions with a brief conversation with Abby at the police station. When she asked Abby again if Thomas had come to bed the night Merritt died, Abby said that he had. However, Detective Henry knew that wasn’t true. Thomas slept with “family friend” Isabel (Isabelle Adjani) at a nearby inn. She caught Abby right in the lie. Detectives Henry and Carter (Michael Beach) arrested Abby for Merritt’s murder.
Merritt had barbiturates in her system the night she died. Thomas had stolen a pill from Amelia’s mom, who was carrying high-dose barbiturates to end her life if her cancer complications worsened.
Abby found her perfect opportunity to make sure she and her baby were set for life when she saw Merritt cut her foot on the beach. Abby grabbed one of Thomas’ stolen pills, crushed it up, and put it in a glass of orange juice. She handed the glass to Merritt, who gulped it down, and the effects were almost immediate. Abby asked Merritt to go for a late-night swim. A woozy Merritt agreed and waded out into the water with Abby.
When Merritt stumbled in the water, Abby grabbed her and pushed her head underwater. Merritt drowned at Abby’s hands. Abby’s child may see the trust fund money, but Abby never will from inside her jail cell.
The Perfect Couple, Streaming Now, Netflix