Last week, The Sinner revealed the answer to its first and most important mystery of why Cora Tannetti (Jessica Biel) killed Frankie Belmont (Eric Todd). She stabbed Frankie seven times on the beach that day because Frankie played a role in the death of Cora's sister Phoebe (Nadia Alexander), a memory Cora had buried but resurfaced when she heard his band's song and saw him making out with a woman. She was triggered to reenact the moment she tried to get him off of Phoebe while he was trying to resuscitate her after her heart stopped while they were having sex, and she happened to have a knife in her hand at the time.
But that's not the USA limited series' only mystery, and heading into Wednesday's finale, there are still a number of questions The Sinner still has to answer. Here's a handy compendium.
1. Why did Cora really do what she did? Or to put it another way, what made Cora have this Pavlovian response to hearing the song and seeing Frankie? Knowing what happened still doesn't totally explain why it happened. Was she programmed somehow? Which leads to our next question...
2. What happened to Cora in the two months she was missing? Cora can't account for the time from that fateful 4th of July weekend to when she showed up in Poughkeepsie. After J.D. bashed her in the head with an ashtray, she seems to have been imprisoned, drugged and possibly tortured by a man in a tan ski mask.
3. Who's the guy in the tan ski mask? And why does being tan make that ski mask so creepy? The guy is wearing scrubs and was ready to give Cora an IV, so there's something quasi-medical going on. Maybe he's med student Frankie?
4. Who's the body in the woods? We presumed that the body Det. Ambrose (Bill Pullman) found in the woods near the school bus was J.D.'s (Jacob Pitts) missing ex-girlfriend Maddie (Danielle Burgess), but after the events of last week, it could very well be Phoebe.
5. What happened to Maddie? Even if the body isn't Maddie, Maddie is still missing. We know that J.D. did not care about Maddie at all, and we saw her terrified in the woods while she and Cora were being "hunted" by somebody, so wherever Maddie is now, it ain't a happy place. Unless there's another crazy twist and Maddie got away.
6. Who killed J.D.? Mason (Christopher Abbott) went to J.D.'s house to kill him and found him already dead. Whodunnit? I really have no idea.
7. Why did Cora's family lie about when Phoebe died? Early in the season, Cora and Phoebe's parents told Ambrose that Phoebe died a month after Cora left. I don't see any reason for them to have lied about this, since they must have known that Phoebe was missing, but they did lie, so they're hiding something.
8. What will happen to Cora? Her fate is up in the air at this point. But everything Ambrose is doing to find an explanation for why Cora did what she did may not matter, because she did kill Frankie Belmont.
9. What will happen to Mason? Cora's husband's life has been destroyed, too. He's going down a dark path, and as he goes further, it's looking less likely that he'll find his way back. He better hope they figure out who actually killed J.D.
10. Will Det. Ambrose ever be able to have a healthy relationship with a woman? Or will he sex-choke himself to death before that happens?
The Sinner's finale airs Wednesday, Sept. 20 at 10/9c on USA.