What is pentobarbital in Netflix’s The Perfect Couple and is it real?

If you’re wondering whether pentobarbital is real, chances are you’ve been watching to the end of The Perfect Couple, the new Netflix murder mystery series based on Elin Hilderbrand’s 2018 book of the same name. 

It’s one of many curveballs thrown in as the plot unravels, centering a wealthy Nantucket family as they prepare for a dream wedding. But the dream soon turns into a nightmare when one of the guests’ bodies washes ashore, sending the characters (and us viewers) down a twisting path of murder, deceit, and family secrets. 

Of course, we don’t find out who the murderer is until The Perfect Couple’s shocking ending, but getting there is a wild ride, made all the more compelling by the show’s killer cast – Nicole Kidman, Liev Schreiber, Eve Hewson, Meghann Fahy, and Dakota Fanning, to name a few.

Dendrie Taylor also stars in the new Netflix series as bride-to-be Amelia’s mom Karen, whose innocuous role in proceedings takes a tragic turn in the finale. Before we get into it, be warned: spoilers ahead! And some may find this content distressing.

Pentobarbital explained

Pentobarbital, or pentobarbitone, is a real drug classified as a barbiturate. Barbiturates are a group of sedative-hypnotic medications that act as central nervous system depressants, meaning they slow down brain activity. 

Initially developed in the early 20th century, pentobarbital was commonly used as a sedative, anesthetic, or anticonvulsant. Its ability to induce sleep and reduce anxiety made it a popular choice in medical settings for many years.

However, barbiturates in general are less common in today’s medical practice due to their high potential for physical and psychological addiction. They’ve largely been replaced by benzodiazepines, including Valium, for a variety of treatments due to their lower risk of addiction and overdose. 

Today, pentobarbital is primarily used in veterinary medicine for anesthesia and euthanasia of animals, as well as in certain human medical contexts such as medically induced comas or to control seizures.

It is also used as part of the protocol for capital punishment in some countries, and can be used for human euthanasia or where physician-assisted dying is legal. Because of its potency, pentobarbital is tightly controlled and is only available by prescription.

The role of it in the series

In Episode 6 of The Perfect Couple, Karen is a cancer patient, and she reveals that she carries three pentobarbital pills with her as a backup plan if her health descends suddenly. 

“They were kind of like a security blanket for me in case things got worse quickly,” she tells her family and the police. 

Karen wanted to keep this secret to herself, hiding the pills in the pouch of her toiletry bag. We see Karen do this at the start of the new series, and it’s more or less forgotten about until the very end – after she discovers the murder victim, Merritt, was found with barbiturates in her system. 

She’s forced to tell her husband and Amelia’s dad Bruce (Michael McGrady) about the pills, who urges her to explain to everyone, including the detectives on the case – although it’s understandably not easy for her. 

When the detectives ask where she got the pentobarbital, Karen explains, “A young man in my cancer support group got them for me. You take three at once.” 

But when it comes to Merritt’s murder, only one had gone missing. “Just one wouldn’t have killed her,” adds Karen. “It would have knocked her out though.” And as Bruce points out, “She was very careful with the pills, officer. She actually kept them separate from the other medications.”

So, what exactly happened? Well, following this revelation, Amelia’s husband-to-be Benji remembers something – his (selfish) older brother likes to play a game called prescription roulette, whereby he sneaks into people’s rooms, steals their meds, and ropes in anyone who wants to “play.”

This leads the detectives to believe Merritt may have unintentionally taken the pentobarbital pill after Thomas stole it from Karen’s belongings. But the real truth eventually comes out – Thomas’ wife, Abby, had used the drug to spike Merritt before drowning her. 

You see, it comes out that Greer’s husband Tag had been having an affair with Merritt, and she was pregnant. 

The Winbury sons were set to receive their trust funds as soon as the youngest turned 18. Up until now, this was 17-year-old Will. But with Merritt’s pregnancy, Thomas (and therefore Abby) would’ve had to wait another 18 years until they could get their mitts on the money. 

However, Abby’s evil plan is thwarted when the detectives connect the dots. Although it won’t bring Merritt back, this does mean she’ll be spending most likely the rest of her life in prison. 

Is euthanasia legal in Nantucket?

Nantucket is an island in Massachusetts, where euthanasia, the practice of intentionally ending life to eliminate pain and suffering, as well as physician-assisted dying is prohibited by law. 

However, following suit from a number of other states, a bill was introduced which would authorize medical aid for dying in Massachusetts.

According to Compassion & Choices, a US nonprofit aiming to improve patient autonomy and individual choice at the end of life, as of 2024, the bill is awaiting action. 

Is it in the book?

Although Karen does have three secret three pills stashed in with her usual pain meds for euthanasia purposes in The Perfect Couple book, these aren’t what are given to Merritt. 

Instead, she is slipped one of Greer’s strong sleeping pills. Similarly to the Netflix series, after being given the pill by Abby, she goes into the water and dies. 

But the biggest change has to be Abby’s intent. As opposed to purposely spiking Merritt in the show and drowning her, Abby drops the pill into Featherleigh’s (the book’s version of Isabel) drink in a bid to stop her from sleeping from her husband Thomas. 

What she doesn’t realize is that Featherleigh actually poured the drink for Merritt. Rather than being murdered, Merritt accidentally drowns, and even once the novel is finished, it’s not revealed whether the detectives find out what really happened. 

The Perfect Couple is streaming on Netflix now. For more Netflix updates, check out everything we know about Virgin River Season 6, Stranger Things Season 5, and Wednesday Season 2. You can also read our roundup of the best shows of 2024 so far, and the TV shows streaming this month.