Harry Ambrose is a mess. By the time we get to The Sinner Season 4, he isn't just retired; he’s practically haunted by the ghosts of Jamie Burns and the trauma of the previous three years. Most crime shows follow a formula where the detective is a hero. Here? Bill Pullman plays Ambrose as a man who is barely holding it together with scotch and insomnia. If you’re looking for a clean, procedurally perfect "whodunnit," you’re watching the wrong show. This season is a "whydunnit" wrapped in the cold, foggy atmosphere of Hanover Island.
People often forget how weird this show gets. Season 1 was about a random stabbing on a beach, but Season 4 pivots to something much more atmospheric and folk-horror adjacent. Ambrose goes to Maine to recover, to find some peace, but instead, he witnesses Percy Muldoon jump off a cliff. Or did he? That’s the hook that keeps you up at 2 AM.
The Haunting of Harry Ambrose in Hanover Island
The setting of Hanover Island is basically a character itself. It's bleak. The lighting is perpetually grey, and the water looks like it would kill you in three minutes. When Percy Muldoon—played with a jittery, tragic energy by Alice Kremelberg—disappears into the surf, the town doesn't just mourn. They close ranks.
Honestly, the Muldoon family is terrifying. They aren’t your typical TV villains. They are a fishing dynasty, led by the matriarch Meg Muldoon (Frances Fisher), who rules the docks with an iron fist. The tension between the Muldoons and the Lams—a rival fishing family—provides the friction that drives the plot. It isn't just about a girl jumping off a cliff; it's about fishing quotas, illegal human smuggling, and the weight of family secrets that span generations.
Ambrose is an outsider here. The local police, specifically Chief Lou Raskin, aren't exactly thrilled to have a pill-popping, retired NYPD detective poking around their business. But Ambrose can’t stop. He’s addicted to the darkness. He sees himself in Percy. He sees his own inability to find peace reflected in her journals and her obsession with Celtic mythology and the "star" she thought was guiding her.
Why Percy Muldoon’s Mystery Hits Different
Most murder mysteries focus on the body. The Sinner Season 4 focuses on the absence. For a large chunk of the season, we don't even know if Percy is dead or alive. We just have these grainy visions Ambrose keeps seeing. Is he hallucinating? Maybe. He’s off his meds and traumatized.
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The show dives deep into the concept of "intergenerational trauma." That's a buzzy phrase these days, but the show handles it with a heavy hand. Percy wasn't just a "troubled girl." She was the pressure valve for a family that had been doing terrible things to stay afloat for decades. When you look at the Lam family, you see the flip side of the American Dream—immigrants who had to make a horrific "deal" with the Muldoons just to survive.
The reveal about Bo Lam is where the season shifts from a mystery to a tragedy. It wasn't some grand conspiracy involving cults or supernatural entities. It was a mistake. A horrible, split-second accident involving a gun and a dispute over a boat. Percy carried that guilt for years. Every time she looked at the Lams, she saw the brother she accidentally killed. That kind of psychological weight is what Derek Simonds, the showrunner, excels at portraying.
Breaking Down the Ending of The Sinner Season 4
If you've finished the finale, you know it isn't a happy one. Ambrose eventually pieces together that the Muldoon family helped cover up Bo Lam’s death years ago to protect Percy. But the cover-up was worse than the crime. It involved human smuggling rings and a web of corruption that eventually strangled Percy’s spirit.
Meg Muldoon’s realization that her "protection" is what actually destroyed her granddaughter is one of the most chilling moments in the series. Frances Fisher plays that scene with a coldness that eventually cracks into pure grief. It’s brutal.
Then there’s the final scene. Ambrose is sitting by the water. He’s talking to the "ghost" of Percy one last time. He asks her if she’s finally found what she was looking for. She asks him if he has. He doesn't answer. He just looks out at the ocean. It’s a perfect, somber ending for a character who has spent four seasons wading through the worst parts of the human psyche.
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The Realism of the Fishing Industry Subplot
One thing the show gets surprisingly right is the desperation of small-town fishing communities. This isn't just window dressing. The struggle for permits, the declining fish stocks, and the way big families squeeze out the newcomers—all of this is based on the real-world tensions in places like Maine and Nova Scotia.
The Lams weren't just "rivals." They were people trying to survive in a system rigged against them. When CJ Lam tries to break free from his family's secrets, you feel the weight of his cultural and familial obligation. It adds a layer of realism that makes the more "thriller" elements of the show feel grounded.
- The Casting: Bill Pullman’s physical acting is underrated. Notice how he walks in Season 4—he looks like he’s carrying a literal weight on his shoulders.
- The Visuals: The use of the color blue and grey creates a sense of drowning throughout the eight episodes.
- The Script: The dialogue is sparse. It relies on what isn't said, which is a bold choice for a mystery show.
What People Often Get Wrong About Season 4
A lot of fans complain that the season is "too slow." They want the adrenaline of Season 1's Cora Tannetti story. But Season 4 is a character study. It’s a slow-burn meditation on guilt. If you’re rushing to find out "who did it," you’re missing the point of the long shots of the shoreline and the quiet conversations in the kitchen.
Another misconception is that the "occult" elements were leading to something supernatural. The Celtic rituals and the statues in the woods weren't about magic. They were Percy's desperate attempt to find a framework for her guilt. She was looking for a way to cleanse herself because the "real" world—the law, her family—offered no path to redemption.
The "Star" wasn't a deity; it was a beacon. It was her hope. And when she realized that no amount of ritual could undo the fact that she killed Bo Lam, she chose the ocean. It’s dark. It’s heavy. But it’s incredibly human.
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Actionable Takeaways for Your Next Rewatch
If you’re planning to dive back into The Sinner Season 4, or if you're watching it for the first time, keep these things in mind to get the most out of the experience:
- Watch Harry’s Hands: Ambrose has a nervous tic with his hands throughout the series. In Season 4, it’s at its worst. It’s a physical manifestation of his internal chaos.
- Listen to the Sound Design: The sound of the wind and the waves is constant. It’s designed to make the viewer feel as isolated as Percy felt.
- Pay Attention to the Lam Family’s Altar: The show drops hints early on about the Lam family’s true history through the way they interact with their traditional mourning practices.
- Track the "Guilt" Timeline: Try to map out when each character learned about Bo Lam’s death. It changes how you view their interactions in the early episodes. Meg Muldoon’s behavior, in particular, becomes much more sinister once you realize she’s been living a lie for years.
The show concludes Harry Ambrose's journey by forcing him to realize that some things can't be "solved." You just have to live with them. It’s a cynical but honest take on the detective genre.
To fully appreciate the narrative arc, compare the first episode of Season 1 with the final episode of Season 4. You see a man who started by trying to save someone else and ended by realizing he might not even be able to save himself. It’s one of the most complete character studies in modern television.
Check the background of the scenes in the Muldoon house; the production design team filled the sets with real Maine fishing artifacts to ensure the atmosphere felt authentic. This attention to detail is why the show feels so lived-in and claustrophobic.
If you are looking for a show that respects your intelligence and doesn't provide easy answers, this is it. Just don't expect to feel "good" when the credits roll. Expect to feel thoughtful.