It isn't a great sign, feeling you have to do homework before watching a new season of a TV show (hi, Ozark). But here we are. The third season of The Sinner left many viewers feeling lukewarm about the police procedural heading into the newest chapter.

If you're embarking on season 4, having forgotten the events of season 3 or having left it alone completely, then this guide is for you. The great news is that the hugely improved season 4, which is already out in its entirety on Netflix, doesn't require much knowledge of what went before. But you might be interested in where police detective Harry Ambrose is at, what headspace he's living in, portrayed so vividly by Bill Pullman, as it somewhat affects the events of the newest chapter.

Here we go.

Note: Spoilers for season 3 lie ahead.

What was the main mystery of season 3?

Season 3 sees Harry Ambrose called to a car accident, where the driver, Nick Haas (Chris Messina) was killed. The man who reported the accident was Jamie Burns (Matt Bomer), a former college friend of Nick's who, on the surface, appears to be a well-put-together guy. It's revealed that Nick unexpectedly visited Jamie and his pregnant wife Leela (Parisa Fitz-Henley) beforehand. It's also later revealed that Jamie intentionally caused the accident and wanted Nick to die.

What was the resolution?

It turns out that Nick had a significant influence on Jamie throughout their college years. Fans of the Übermensch concept in the philosophy of Nietzsche, the pair believe in nonconformity, with Nick pushing Jamie to kill and indulge his wild side. This comes to a head when, years later, Nick returns to Jamie's life and pushes him once more. This time, their random target is artist Sonya (Jessica Hecht). But the conflicted Jamie refuses, killing Nick instead in the car crash so that their secrets die with him.

How did Harry and Sonya get together?

Sonya was a random target of Jamie's. Harry and Sonya start dating during the investigation. When Jamie later threatens Sonya, Sonya manages to talk to him long enough to keep herself alive. She's still with Harry months after the end of the investigation, comforting him when he breaks down over the experience.

How did the events of season 3 affect Harry?

Aside from meeting his new partner in artist Sonya, season 3 saw Harry pushed to the extremes. Jamie provoked Harry to attack him in front of Harry's grandson Eli, causing Harry's daughter Melanie to prevent Harry from seeing Eli. Not to mention Harry being buried alive in a twisted game with Jamie (Harry survives).

Jamie attempts to influence Harry in his wild ways, in living life with a different philosophy. But after secretly recording Jamie's confession to murder, Harry sees Jamie turn against him. An unhinged Jamie kills Harry's boss and goes after everyone Harry loves, including Sonya and Eli. Jamie even shoots Harry. To protect his family and egged on by Jamie's taunts, Harry shoots Jamie, even though Jamie wasn't physically attacking him.

Harry watches a frightened Jamie die by his hand and, months later, is still traumatized by the events. By the beginning of season 4, we discover Harry has now retired from police duty and experiences visions once he starts up on another case.