After months spent dodging spoilers from our friends across the pond, The Sinner is finally available to stream on Netflix for fans here in the UK.
The anthology series stars Bill Pullman as detective Harry Ambrose, who spends each season trying to understand the motives behind a person's extreme actions.
This time around, he's looking into the apparent suicide of Percy Muldoon (Alice Kremelberg), the youngest daughter of a successful fishing family on Hanover Island, Maine.
This will be his final case on the small screen, as The Sinner's domestic broadcaster USA Network confirmed last year that the show would not be returning for a fifth season.
"It’s been a huge pleasure and a privilege to be able to tell the kind of stories we have on The Sinner these past four seasons," said series creator Derek Simonds.
"[Universal Content Productions] and USA have been ideal partners and continually supportive of our creative goals, and I’m so pleased to complete Harry Ambrose’s dramatic series-long arc as we intended in this final season."
Here's everything you need to know about The Sinner season 4 as it finally launches in the UK.
The Sinner season 4 Netflix release date
The Sinner season 4 is available to stream now on Netflix UK and Ireland, having launched on the service on Wednesday 26th January 2022.
Previously, the show had been broadcast in North America on cable channel USA Network, where it premiered on Wednesday 13th October 2021 and concluded at the start of December.
As a result, British fans have had to be careful to avoid spoilers for this season's mystery, but can finally join the conversation by binge-watching this week.
Filming on The Sinner's final season took place between April and August 2021, primarily in Nova Scotia, Canada.
What's The Sinner about?
The Sinner is a crime mystery series that caught fans' attention in season one by flipping the 'whodunnit' format into a 'why-dunnit'. Jessica Biel plays a woman who, in one of the most shocking and gripping starts to a series we've ever seen, stabs a man to death on a beach. But has absolutely no idea why she did it. The series then unpicks the crime over eight episodes.
Season two tells a completely different story, but maintains the same sense of intrigue. This time we're focusing on a child criminal, a 13-year old boy who is suspected of killing his parents in their motel room.
The Sinner season 4 cast
Each season of The Sinner is intended to be a 'closed-ended' story, which is part of the appeal for fans.
But while the crimes and most of the cast are different every time, the investigator stays the same: the one and only Harry Ambrose, played by Bill Pullman.
Each previous season has usually focused on one central character played by big-name stars such as Jessica Biel (who still acts as executive producer on the series) and Chris Messina, but season 4 looks to move towards an ensemble cast.
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The first new cast member for season 4 was confirmed as Alice Kremelberg, who you'll know from The Trial of The Chicago 7. She plays a "tough" but "charismatic" woman called Percy Muldoon, who is a trailblazer in the male-dominated world of lobster fishing. Life is good, until an awful tragedy changes her world forever...
Watchmen star Frances Fisher will appear as Meg Muldoon, Percy's defensive mother who refuses to believe that her accident was a suicide.
Kremelberg and Fisher will be joined by Mare of Easttown star Neal Huff as Sean Muldoon, a fellow lobster fisher in the family business with a sensitive soul.
More names were announced in June 2021, including The Flight Attendant's Cindy Cheung as Stephanie, who will do anything to protect her son CJ after he becomes embroiled in the mystery.
CJ himself will be torn between will be supporting his parents on the island and starting a new life on the mainland, and will be played by Baby's David Huynh. The Man in the High Castle star Ronin Wong will complete the family as restaurant owner Mike, who is often made to feel like an outsider compared to the long-term residents.
Finally On the Basis of Sex's Joe Cobden has been cast in the recurring role of Lou Raskin, the local Chief of Police who knows most of the island's residents by name.
What happened in The Sinner season 3?
**Warning – spoilers ahead for season 3**
Season 3 of The Sinner saw Detective Harry Ambrose investigate a tragic car crash in upstate New York that turned out to be much more sinister than initially thought.
Nick Haas (Chris Messina), who was driving the car, was killed in the accident while the passenger, his friend from college Jamie Burns (Matt Bomer) survived and reported the accident.
It is revealed that Jamie intentionally caused the accident and while Nick initially survived, Jamie delayed calling the emergency services to ensure Nick's death. Nick was on his way to see Sonya (Jessica Hecht), the nearest resident to the scene of the accident, and intended to bury her alive. Sonya finds a freshly dug grave on her property and a jacket on the shovel, leading Harry to believe Jamie dug the hole.
Harry starts tracking Jamie's phone, and follows him into New York City where he goes to a party and meets Kyle, a medium, who senses that Nick is still part of him. The next day, Harry is called to the scene of Kyle's murder.
It is revealed that Jamie bludgeoned Kyle to death after after Kyle started reciting phrases that Nick used and disposed of the bloody evidence. Jamie's wife Leela (Parisa Fitz-Henley) kicks him out of the house after Sonya tells her what she knows about Jamie's involvement in the investigation, and he starts stalking Harry and Sonya, who begin dating.
Jamie tells Leela he killed Kyle and gives a written confession to Harry, who he then buries alive in the pit him and Nick dug for Sonya as part of a trust exercise he used to do with Nick. After eight hours, he digs Harry up and has Harry burn his confession. He then tells Harry that Nick had wanted Jamie to be the one to kill Sonya and forced him to crash the car and let him die. It turns out that Harry had been recording their conversation on his phone in which Jamie confessed to manslaughter and asks Detective Vic Soto (Eddie Martinez) to arrest Jamie but due to the nature of the investigation, a judge releases him.
Jamie becomes fully unhinged, kills Harry's boss Morris and plans to kill everyone Ambrose cares about. Jamie retrieves Harry's grandson Eli from his karate class and goes to Sonya's house to attack her, but the police arrives in time to save her. Jamie flees the scene with Eli and and Harry tracks him down, but is ambushed by Jamie who takes his gun away.
After playing psychological games with one another, Jamie grows increasingly psychotic and shoots Harry in the arm. Harry runs out into the woods pursued by Jamie but Jamie eventually surrenders and taunts the detective by saying that he'll never be content after locking him away. However, Harry responds by shooting Jamie in the abdomen and he dies before an ambulance arrives.
Harry is left racked with guilt but doesn't turn himself in. Instead, he goes to see Sonya and breaks down in her kitchen.
If you're confused by the ending, here's our helpful guide to The Sinner season 3 ending explained.
The Sinner season 4 plot
As expected, the fourth instalment will explore how Harry's actions in season 3 have affected his psyche and judgement as he begins to question his own mind.
Season 4 looks to alter the 'whydunnit' formula slightly, starting not with a murder but a potential suicide that soon turns into a missing person investigation. The tortured Detective Harry Ambrose is now retired and recuperating in Hanover Island in Main with his wife Sonya, when he sees Percy Muldoon, the daughter of an affluent family, walk off a cliff.
However when authorities are unable to find a body and an eyewitness even claims to have seen Percy drive away, Harry begins to question whether what he saw was even real.
Percy's mother Meg refuses to believe her daughter would kill herself - and clearly knows more than she's letting on. After discovering a creepy message on a boat and witnessing local tensions rise, Harry is soon caught in yet another mind-bending mystery which is sure to only increase his paranoia further.
The Sinner season 4 trailer
The trailer was released in September 2021, and neatly outlines this season's premise. Watch below.