Why Did Cora Commit The Murder On USA Network’s ‘Sinner’?

USA Network’s Jessica Biel drama, The Sinner, is the highest rated new cable drama of 2017, and it’s ratings have inched up each week since its debut. There’s a good reason for that, too: It’s not only riveting television, but it features an engrossing, mysterious murder investigation harder to crack than anything since the first season of True Detective. It’s Peak TV catnip; every answer only raises more questions, and halfway through the 8-episode limited series, viewers are as confused as they were after the opening episode.

The Murder

The opening episode presents a fairly cut-and-dry case. Cora Tannetti (Biel) is not feeling like herself one day, and on a visit to the beach, she abruptly stabs and kills a man named Frankie. At the time, Frankie was aggressively making out with his girlfriend, and a song that they were playing clearly triggered Cora. We know this because, during an interrogation with Detective Frank Ambrose (Bill Pulmann), Cora loses it when Ambrose plays the song again and Cora punches Ambrose seven times, in the exact same pattern that she stabbed Frankie.

There are a number of witnesses to the murder of Frankie. Cora does not deny murdering Frankie. Open and shut, right

Clearly not, as there’s no motive for the murder, and not even Cora understands why she did it. We do know that Frankie seemed to recognize Cora and, in fact, seemed relieved to die, according to an eyewitness account.

July 2012

After providing Detective Ambrose with a story made up of mostly false memories, the most recent episode — Part IV — began to zero in on Cora’s motive. It has to do with a two-month period beginning on July 3, 2012, of which Cora has no memory. Based on memories retrieved with the aide of a psychotherapist, we know (or think we know) a few things:

— Cora was being tormented by a man named J.D. (Justified’s Jacob Pitts) and his ex-girlfriend, Maddie (Danielle Burgess). The relationship between Cora and Maddie is confusing. Maddie seems to hate Cora, but Cora also seems protective of Maddie, and on the night in question — July 3, 2012 — Maddie offers Cora a mysterious pill at a bar called The Taproom. Cora ingests it, but it is Maddie who seems to be suffering from the effects of the drug on the dance floor.

— Once they leave the bar, J.D. siphons gas from another car, and they travel to a second location. Maddie doesn’t want to go, because she is afraid she will die. In one memory, however, Maddie seems to fear that Cora will kill her.

— The second location is a house which features wallpaper that has been haunting Cora’s memories. There, Cora also hears the song that triggered her into killing both Frankie and assaulting Detective Ambrose. At the house, it appears that Cora is violently sexually assaulted by someone in a terrifying ski mask (perhaps it is J.D., but I think it may be Cora’s present-day husband, Mason).

— Cora also has a memory of herself at the house stepping on and crushing Maddie’s sternum, presumably killing Maddie.

— Meanwhile, in a second set of memories from that same night, both Cora and Maddie are stuck in a muddy water out in the woods. Maddie tells Cora that they poisoned her and that she is going to die. Meanwhile, there are also people hunting for Maddie and Cora out in the woods. They fire at least two shots at them.

— In the present day, Detective Ambrose is able to piece enough of Cora’s memories together to deduce her location in the woods. He goes to that location and finds the remains of a body, possibly Maddie’s.

— Ambrose also finds an abandoned school bus in that location. We don’t know exactly how that plays into the mystery, but we do see repeatedly in Cora’s retrieved memories a school bus passing her by when she’s a kid.

— In the present day, we also learn from Maddie and J.D.’s landlord, Debra Randall (Pamela J. Gray), that J.D. and Debra sought a polyamorous relationship with her (she declined).

— Cora has track marks on her arms in the present day and, after her two-month disappearance, she checked into a rehab for heroin addiction. However, Cora kicks the addiction easily, and in the present day, Ambrose discovers that Cora has no idea how to shoot up heroin. It’s clear that Cora believes she became a heroin addict during her two-month blackout, but in reality, she never took heroin. The track marks are a result of some other unknown cause (perhaps a transfusion).

Cora’s Childhood

There are layers to this mystery, as well. It’s not as simple as “Cora murdered Frankie because she was triggered by a song because of a trauma she suffered in July 2012.” Cora’s childhood also plays a role. As a child, Cora’s sister Phoebe nearly died in childbirth. Phoebe remained sick her entire life. Cora’s very strict, very religious parents drew a straight line between Cora’s “sins” (minor infractions, like eating chocolate) to the state of her sister’s health. At some point in her teenage years, Phoebe died. Her parents may or may not have blamed Cora’s rejection of their religion for Phoebe’s death.

— It is also heavily hinted at that Cora’s father sexually assaulted her as a child.

— Despite her ill health and her parent’s strict religious beliefs, Phoebe is weirdly obsessed with porn. She has porn magazines, and likes to watch porn on her computer. As a kid, Phoebe also encourages Cora to go out and have sex with a neighbor kid so that Cora can report back to Phoebe the details.

— Much to Cora’s dismay, her father was having an affair with a neighbor lady when she was around 13. Phoebe seems completely unbothered by the affair.

Cora’s Husband

Cora’s husband, Mason (Girls‘ Christopher Abbott), also seems to figure into this story somehow. He is shocked and horrified when Cora murders Frankie. He doesn’t understand why, but as he learns more about the case, Mason seems to believe that J.D. is entirely responsible. Mason, who met Cora soon after her two-month blackout, is trying to pin the murder of Frankie on the influence of J.D. Not only does Mason seems very invested in blaming this all on J.D., he advises Cora against using a psycho-therapist to recover her lost memories.

Mason seems somehow involved, and he seems to be trying to cover up Cora’s past.

Why Did Cora Kill Frankie

It’s too early to draw any definitive conclusions, but clearly Cora’s traumatic childhood and her two-month blackout hold the secrets to the murder. The crucial detail here is that she is triggered by a song and someone wants her to believe that she was a heroin addict during her blackout. Based on her childhood, her mother also tried to convince Cora that Phoebe’s life depends on Cora doing whatever is asked of her by “God.”

My guess is that while J.D. may have played a role, the real villain here is Cora’s mother. I think that Cora was hypnotized (she was put under a hypnotic spell after taking the pill that “the song” is her trigger), and that under the influence of hypnotherapy, Cora’s mother demanded that Cora murder Maddie and carry out any other number of sacrifices on behalf of whatever entity Cora’s mother believes allowed Phoebe to live. Cora’s mother clearly paid a debt to some religious entity for the life of Phoebe (or believes she did), and also felt that Cora owed that debt.

In exchange for Phoebe’s life, I think Cora’s mother sold Cora out to be raped by multiple men. I also think the track marks are not the result of heroin, but from multiple transfusions Cora’s mother forced upon her to save Phoebe’s life. I am fairly certain that Mason was also somehow involved, as well. Mason, recall, made no attempt to prevent Cora from murdering Frankie until Frankie had already been dealt the lethal stabs, plus he’s trying to hide Cora’s past from her and quickly pin the entire ordeal on J.D. I think that Mason may have been one of the men who raped Cora in 2012.

It’s still very convoluted, and there are a number of false memories to contend with, so it’s hard to say exactly what happened. However, I am convinced that Cora’s mother and Mason were in cahoots, and that everything done to Cora was in an effort to save Phoebe’s life.