From EW.com
https://ew.com/recap/the-sinner-season-1-finale/

The Sinner S1 Ep 8
*******

The Sinner finale recap: 'Part VIII'

The identity of Cora's masked captor is revealed at last
By Molly Fitzpatrick
September 20, 2017 at 11:01 PM EDT

CREDIT: PETER KRAMER/USA NETWORK

The Sinner
S1 E8

After nearly two months (the same length of time Cora was held prisoner by that mysterious masked man — coincidence?!), The Sinner has gone a long way toward winning me over. That’s not say it shouldn’t have been about half as many episodes long, with half as many abrupt flashbacks. But going into “Part VIII,” the very last episode of the season, I’m pleasantly surprised that I have no idea what’s about to happen.

We’re back in that cursed Beverwyck basement, this time in the present day. Cora, distraught, remembers now. She blames herself for Phoebe’s death, and for Frankie Belmont’s, too — he was only trying to save her sister. But what happened next, after J.D. hit her with the ashtray? She still doesn’t know. Nevertheless, Ambrose is optimistic, telling her he’ll find a witness from that night. She has a motive, which means she has a defense.

Or does she? Ambrose is a little disappointed to learn that nothing like the telltale wallpaper from Cora’s memories was ever seen in the Beverwyck basement. Farmer reports that there’s no trace of Cora’s DNA in the room, though the body found in the woods is indeed Phoebe’s. As for Creepy Todd, who seems like exactly the kind of guy who would abduct a woman and imprison her at length (that Todd!), he died two years ago — but more importantly, the day after Phoebe’s death, he took his wife to renew their vows in the Caribbean (LOL), where they remained for the following month.

Ambrose does have one promising lead, though. Authorities have identified one of the two men who fled the murder scene at J.D.’s house as Daniel Burrows, a.k.a. Duffy. Officer Caitlin finds his rental van parked in front of a shifty storefront for the “American Medical Clinic.” Ambrose enters, without waiting for backup. (His beard deflects bullets, you see.) The waiting room is full of women, all of whom eye him suspiciously. In case there was still any doubt that criminal activity was occurring on the premises, the extremely unchill receptionist leaps to his feet and tells Ambrose, “This is a private business. You’ve got to leave.” But before he can do anything, Duffy arrives — only to run right back out when Ambrose calls him by his name, just as more cruisers drive up. Duffy is shot by Caitlin when he pulls a gun.

Well, that’s one more potential witness down. Ambrose sits in on the interrogation of the man who was working the clinic desk. He explains that these women were hired to pick up prescription drugs from pharmacies, using scripts J.D. writes with license numbers defrauded from doctors. The receptionist says he had nothing to do with J.D.’s death, that Duffy killed him because all the police activity buzzing around J.D. made him nervous. Ambrose finds this hard to believe — there must be some connection to Cora Tannetti. He catches his favorite inmate up on his non-progress. She doesn’t understand why she can’t just tell the judge what happened — her sentencing is tomorrow. That won’t work, says Ambrose. Without a witness, she won’t be believed.

Cora has another visitor — holy s—, it’s her mother. Make no mistake, this isn’t a happy reunion. Mother Lacey thinks Cora is as “disgusting” as ever. Cora tells her she doesn’t regret taking Phoebe out. She fell in love, she had sex, she died the way she would have wanted. “I’ve never seen her happier than that night,” Cora says. Her mother reminds her that Phoebe was buried in the woods, in the dirt, alone. (Good point!) Cora asks her why she didn’t call the police when they didn’t come home. (Extremely good point!) Mom thought they ran away — she’d heard them whispering about Florida all those years, which clearly didn’t do anything to further endear her to her elder daughter. Womp womp. “I’m more free now than I ever was with you,” Cora tells her.

At the sentencing, Cora can’t restrain herself from rising to her feet and addressing the court. She apologizes to the Belmont family, then makes a last-ditch plea for clemency. “Somebody took my sister and buried her in the woods and they kept me in a room for months and I don’t even know what they did to me and they’re out there,” she cries. Hmm. It occurs to me that if you haven’t watched seven and a half episodes of a miniseries building this very story line, that might sound a little nuts. Anyway, this statement is too little too late — Cora already waived her right to a trial. The judge sentences her to a minimum of 30 years in prison.

Fortunately, Cora’s next prison visit is a much happier one. Mason finally brings Laine to see her. She scoops her son up into her arms. The three enjoy a nice family moment — perhaps the series’ very first, given how depressed Cora was from the very beginning — as Laine colors and his parents chat about his good performance in school. But Cora isn’t sure if it’s right to bring him here, right for the difficulty of her incarceration to keep hurting both Laine and Mason. Her husband firmly disagrees. Laine needs his mom; they’ll come to see her every week. Awww, Mason. I like you so much more when you’re not in Junior Detective vigilante justice mode.

Meanwhile, Ambrose seems like he’s taking Cora’s sentence at least as hard as she is, staring into space both out in nature, as is his custom, and in his office, which is new. He’s not ready to give up yet. He manages to track down new mom Maddie Beecham — her name long ago changed, to escape JD — by searching birth records for babies named Winter, the name she would have given her child with everyone’s favorite dealer slash abuser. That night at the Beverwyck, she left early, right after her fight with J.D., and took a bus to Vermont the next morning. J.D. kept calling and calling, eventually asking for her help with a “new business opportunity” — namely, selling Oxy, which wasn’t among J.D.’s wares until after that night. Ambrose’s face changes, hearing this, like all of his beard hairs are standing on end at once. 

Cora, in cuffs, is driven to a swanky home, swarming with cops. Ambrose is waiting for her — this is the Belmonts’ house. Inside, Patrick Belmont is demanding to talk to his lawyer, but he shuts up immediately as soon as he sees Cora. Ambrose takes Cora on a tour of the property, like the least upbeat real estate broker of all time. After two large, bright bedrooms fail to jog her memory, she comes across a smaller, dimmer room, with just one small window obscured with blinds. Cora peels back the slightly frayed edge of the neutral wallpaper to reveal, beneath it, the unmistakable pattern that’s haunted her nightmares for the last five years. Her eyes well with tears of recognition.

A flashback to the Beverwyck reveals that Frankie called his father in desperation in the middle of the night. Patrick raced over to the club to find Phoebe dead and Cora bloodied and unconscious (thanks for the massive head wound, J.D.!). Frankie wanted to take them to the hospital. J.D., unsurprisingly, was less keen on the idea. If the police get involved, he tells Patrick, he’ll just have to inform them that his son was “balls deep in this very sick girl,” stoned out of her mind. Not the best look. Mr. Belmont, thinking of nothing but protecting his son, tells Frankie to go home. He stays behind with J.D., and they drive Phoebe and Cora in the trunk of a car out to the abandoned school bus in the woods. Cora, now somewhat awake, watches the men dig a shallow grave and deposit her sister’s body in it. As she crawls feebly toward the bus, Belmont raises the shovel as if to finish her off, too. But he can’t bring himself to do it. The next morning, he’s tending to her wounds in his own home, to his wife’s horror. Belmont refuses to bring her to the hospital; he’s in too deep now. They send Frankie back to L.A. on the first flight out.

And so the man wearing scrubs and a creepy mask was none other than Patrick Belmont, the father of the man she’d stab to death on a beach five years later. In many ways, he treated his patient slash prisoner with concern and kindness, neatly dressing her wound, gently brushing her hair, and sponge-bathing her, yet — in an ultimately successful effort to wipe her memory and protect his family — shooting her up over and over again, leaving the gruesome scars on her arms that at first made Ambrose peg her for a heroin addict. Once her physical wounds were healed and her addled mind had lost its grasp on Phoebe’s death and the events that followed, he dropped her on the street in Poughkeepsie for a good Samaritan to find.

Our old pal Harry Ambrose determined that the stolen license numbers used by J.D. and company all came from Belmont’s colleagues. Guess who had been blackmailing him? Rest in peace, J.D.: You’re the worst, even in death. Cora studies Patrick Belmont’s face. She knows it was him. She remembers his eyes. “I know you did it for your son,” she says. He tells her he’s sorry and begins to sob. (This effective admission of guilt sure seems convenient for Cora, given that Belmont’s extremely improbable crimes against her might have been hard to prove otherwise?)

Driving away, Ambrose tells Cora that, when they first met, he saw himself in her. “The thing is, what somebody did to us when we were young, I know it wasn’t our fault, I know we didn’t do anything wrong, but somehow I — I don’t know what to do with it all.” Hold the phone, Ambrose. We’d kind of figured out that you were a troubled guy by now — my personal favorite piece of evidence to that point being the time you watered your estranged wife’s trees in the rain while screaming — but you’re just going to put that out there and not tell us what happened?

Back in court, Cora’s public defender (who, until now, was worth no more than her price tag of free) passionately and effectively argues on her client’s behalf, touting Cora’s determination to get clean and lead a normal life in the face of lifelong, unimaginable abuse. The sight of Frankie on the beach triggered her in ways she couldn’t have imagined. Given the new evidence that Cora was “under the influence of extreme emotional disturbance,” the judge reduces her conviction from murder in the second degree to manslaughter. “And rather than spend another day in prison, I hereby order Mrs. Tannetti to be transferred to a secure psychiatric facility,” she says. There, Cora’s case will be reviewed every two years, with the possibility of release if she’s no longer deemed a danger to society or to herself.

Short of a literal fairytale ending in which Cora is discovered to be a long-lost foreign princess and immediately absolved of her crimes thanks to diplomatic immunity (and also, surprise, she has magic powers), this is the very best of best-case scenarios. As she’s led out to the van that will presumably take her to this psychiatric facility, she finds Ambrose waiting for her. They share a hug. Their friendship, if you can call that, has been the most intimate relationship either of them has had in a long time. He promises to check in on her.

But Ambrose has unspoken trauma of his own yet to process, and there’s no telling whether he’ll find a path to absolution like Cora has. Ambrose climbs into his car in the courthouse parking lot. After a few quiet moments, he gazes at his bruised, broken fingernails.