SPOILER ALERT: Do not read if you have not yet watched the second season premiere of “The Sinner,” which aired Aug. 1 on USA.

Detective Harry Ambrose’s (Bill Pullman) willingness to go above and beyond the “who, what and when” of a crime to get to the “why” drove the narrative in the first season of USA’s psychological anthology mystery, “The Sinner.” But from a storytelling standpoint, it also set him up as a specific kind of cop — the kind that cares more about those who have been through trauma perhaps because of trauma he, too, has been through.

The second season of “The Sinner” is doubling down on the depiction of trauma in its characters’ pasts. When Ambrose gets called back to his hometown to investigate a double homicide committed by a teenage boy, he ends up exploring not just the murderer’s past but his own.

“We talked a lot in season 1 about some sources of what was eating away at [Ambrose], but we hadn’t really resolved exactly what the situation was,” Pullman tells Variety. “What we’re seeing in season 2 is that it starts to become clear it’s going back to when he was young. … [It] goes back to when he was in a foster home and the reasons why he was in there. We isolate the event [of] what happened back then that was the traumatizing thing.”

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Here, Pullman talks with Variety about exploring Ambrose’s past, his biggest challenges, and working with Carrie Coon.

Turmoil in Ambrose’s past was certainly seeded in season 1 but how much did you feel you needed to know upfront about where he came from and where he was going once you knew season 2 would dive deeper into the details?

I didn’t want to get the sole thinking on where everything is going and would resolve because it allows me to be in the moment and be in a situation that I feel like is more honest. [It’s also one] that you find in life, which is that you don’t know. Especially this season, where there’s many characters that have demands on his energy and focus, like in life, there’s maybe a couple of people that are potentially the ones who could really open him up.

How do you compare the Ambrose the audience meets in the first episode of the second season to the Ambrose that gets explored as episodes unfold?

He’s definitely attempting to live his life standing on the rails, which you kind of see from the first episode. He’s found some boundaries, and he’s remaining more insulated. But the nature of going to stay at his friend’s house, which means sharing bathrooms, and all of [those] things and appearing kind of wanting to be a normal person means that acting out of all of that, putting on the face of all of that, is really what he’s trying to do, but it doesn’t really work that well. … Something happens to him where you don’t really know the full extent of what happened to him up until the very end. All of that is still down the pike for him. The first three are [him] in a way living in denial. All the pressures of who he is and the naming of what happened, the sense of being around this environment…he’s walking the same walks that he did as a young boy. So [how] those things are starting to pop into his consciousness are happening more and more.

What do you think are some of Ambrose’s biggest challenges this season?

The nature of going back to his hometown and getting into a lot of ghosts that are still haunting him from that time. There is quite a bit that was just referenced in one of the last episodes of last year. He was in the car with [Cora] and they shared a lot of things, and he said, “Not everybody starts out the same way, and you and I both know that.” And whatever he’s wrestling with [from] when he was younger, they had [something] in common, and in a level of sharing that, it brings him to a level of intimacy that really hadn’t happened for him. So, going back to the site of where a lot of his unresolved issues are, I think, bring [them] right to the surface in the relationship with the boy and with the leader of the community, Vera [Coon].

How do some of these new relationships change or explore new sides to Ambrose?

[He’s] in contact with a lot more individuals than he had before, but I think it makes for a lot more energy because the conflict can turn in any direction. … With the boy there’s a level of challenge with the level of communication he’s going to be able to establish. … With his best friend, there’s somebody who has known him and can call him out for things that were in his character all his life. Somebody that has that perspective really can have authority when they start getting into each others’ stuff. Vera has evolved capabilities to kind of look at stuff and see where their flat tires are, and so she can call him out more than anybody else. There’s a lot more people who’s looking to kind of name what’s wrong with him. He can’t hide anymore.

What were your main challenges as an actor this season?

In some ways the challenge of trying to evolve with this person. Vera represents a very specific challenge in trying to uncover what happened to the boy and what caused him to poison and be charged with murder. But at the same time they have this kind of level of intimacy, too. And I think that’s been kind of challenging in that it’s a dual purpose in terms of how much to reveal to each other and how much to trust each other has made some of those scenes particularly challenging.

Why do you think Ambrose stays in his hometown, even when it’s a place so filled with bad memories?

Once you open that door and you step back to that time — that period — and you’re back in that environment, it would be really difficult to just escape it all. There’s some level where he’s reached his Waterloo; the battle is here. [He’s] looking to resolve a lot of issues of what it is that’s made him uncomfortable in his own skin — he doesn’t want to live in that place any longer — and by staying there he’s more likely to resolve it than any other place.

Given that this is an anthology series that has threaded your character through both seasons so far, would you sign on for even more?

Derek [Simonds, executive producer] and I have talked about different things that he’s thinking about, and he does have a kind of trilogy idea so far, and the idea of going to a third season would be very tempting, particularly with what scale he’s talking about going to. I would be interested, for sure. It’s really intriguing, and I have to tell you I had not expected to come to a project like this at this stage in the game. I’ve done a lot of movies, I’ve done a lot of things, but being my age [and playing a character] in crisis and in a situation that really evolves a lot — it’s basically noir to me, which I think is one of the core genres that I’m interested in in all different projects, but this is more detailed and there’s a level of refinement of character that I find. It’s a real gift to get at this point.

“The Sinner” airs Wednesdays at 10 p.m. on USA.