When “Rectify” premiered, television was in a very different place. The acclaimed Sundance drama, which begins its fourth and final season Wednesday, arrived to little notice in the spring of 2013, as the industry was about to plunge into one of its most exciting transitions.

BBC America’s “Orphan Black” and Sundance’s “Top of the Lake” debuted around the same time, and Netflix’s “Orange Is the New Black” turned up a few months later. Those shows — part of a wave of rambunctious and radical comedies and dramas on streaming platforms, cable networks and broadcast that altered our understanding of what’s possible in the TV realm — represented a turning point. They signaled that TV was pursuing a wider array of protagonists — many of them women and people of color — and shifting away from the kind of antihero dramas that defined the aughts. You only have to look at a list of Emmy winners from a decade ago versus 2016 to see how much the industry has changed, largely for the better.

In many ways, “Rectify” — though its initial premise concerned the travails of a troubled white man — has served as the harbinger of many of those changes. As has been the case with the best shows of the last few years, it displays an admirable focus and a rigorous yet flexible devotion to very distinct characters. Shot on location in Georgia, imbued with an unrushed, contemplative tone, and exceptionally wise about the unpredictable processes of grief and acceptance, it is easily one of the finest dramas of the past 20 years.

“Rectify” is the story of Daniel Holden (Aden Young), a death-row prisoner released after years of legal appeals, which were pursued largely due to the ferocious efforts of his family. It has never depicted the crime at the center of the drama in an exploitative way, even as it examines ideas of consent, coercion, violence, and assault.

You could say that “Rectify” is a murder mystery in which we may never truly know who did it, but that was never the point. Creator Ray McKinnon has found thoughtful ways to illuminate Daniel’s possible guilt or innocence, but has also used the story to consider the repercussions of moral choices among a fascinating group of grounded, realistic characters.

Much of the series revolved around Daniel’s difficult re-entry to society, and the ways in which his dislocating presence affected his family and Paulie, the small town in which he lived. Though it often depicts intense situations, “Rectify” always had a light touch and a spirit of quiet, compassionate observation. As the drama expanded the web of relationships it put under a microscope, McKinnon and his cast were always willing to explore the silences between people who love each other — or hate each other — but are often, understandably, at a loss for words.

“What was wonderful in working with Ray was that it was never about what we were saying — it was what was in between the lines,” says Clayne Crawford, who plays Daniel’s stepbrother Teddy (and who also co-stars in Fox’s “Lethal Weapon”). “Rarely do we communicate in a true situation where the stakes are raised and there are repercussions. Rarely do we say what we feel. We’re just trying to navigate it in the best way that suits us, or that protects the individual we love. With each script, it wasn’t about what I was going to say, it’s what I was not saying.”

One of the exceptional things about “Rectify” was the way it gently but persistently expanded the focus of the show without diluting its themes. Every character has been altered over the course of the show’s run, none more than Teddy, a man who found that his embrace of a conventional middle-class life and all the trappings of Southern masculinity couldn’t fill the emotional void inside him or reliably hide his emotional distress.

“I’ve spent my whole life trying to cover up insecurities, especially growing up in a small town in Alabama,” Crawford says. But “Rectify” continually pushes past the masks that its characters wear to grasp at pieces of the difficult, complicated truths below those facades. As Crawford notes, “To explore the vulnerability of Teddy over these past five years has just been incredible. It’s been painful and uncomfortable too, but not only am I a different actor, I’m a different human being as a result of this.”

Abigail Spencer, who plays Daniel’s sister, Amantha (and is a lead in NBC’s “Timeless”), may well have the biggest challenge in the new season. Daniel has moved out of Paulie, and is building a new life for himself in Nashville, while Amantha is drifting.

“It’s a great fall for her, because she had this goal [to free her brother], and it was all-consuming, and who is she without it?” Spencer says. “What’s been so difficult for Amantha is realizing how damaged he really was. I think she was so devoted to the goal of getting him free — the family as a whole was — and I feel like we really start to lean into that [realization] a little more. How damaged he was, and how did we not comprehend that? We couldn’t comprehend it. That’s part of the realization [this season], and that’s part of the process for Amantha to deal with her own stuff.”

She adds with a laugh, “I mean, when we meet Amantha this go-round, she’s going to be smoking a lot of pot. She’s going to be stoned.”

Daniel’s adjustment to Nashville is rough; the first episode of the new season shows him attempting to conform to the rules of a halfway house for former prisoners, and it’s a difficult process. In the show’s timeline, he has been out of prison for a few months, and reintegrating himself into society after 19 years isn’t easy. The halfway house has rules and procedures that cover employment and each resident’s duties, and Daniel finds those regulations and new relationships tough to deal with.

“Someone like Daniel ultimately needs to be his own person, but because he is so damaged and challenged by what’s happened to him, he also needs a design for living, a structure and consistency, and that will be part of the tension of the season,” McKinnon says. “For some people, [a job] is a means to an end; you make money, and then you can give shelter to your family and feed your family. For others, they need to do work that is immensely gratifying to them, and it’s not about the money as much as it is the journey of that vocation. So those are things Daniel will be dealing with, and they are different from what we dealt with in the previous seasons.”

Daniel’s absence from Paulie also changes things for the family members left there. “Daniel is not dealing with the projections of his family and of the town upon him,” McKinnon notes. “What’s interesting was not just to pluck him out of there and place him in a new world, but also, he was the center of the storm around [that family, and we wanted to see] what they would do once the center was removed — how they would react. So that was fun to explore, and is a big part of the final season.”

Teddy, who’s back in Paulie but last season went through a break-up with his wife, Tawney (Adelaide Clemons), “is the kind of individual that tries to embody others’ ideas of who he is,” notes Crawford. “What’s been so nice about this journey, and especially this final season, is that Teddy truly is, probably for the first time in his life, looking at himself and looking internally. ‘Who am I and what do I want?'”

By being so careful about how it depicts the characters’ emotional states, and by giving each important moment and connection room to reverberate, “Rectify” also allows the audience to go on an exceptional journey. It may be the least manipulative show on the air, but when its characters feel something — whether it’s relief, sadness, wonder or despair — that mental and spiritual energy almost bleeds right through the screen. It’s not just a show that depicts Southerners with dignity; it’s not just a show that inhabits small-town life without an ounce of condescension; and it’s not just a show that examines the effects of violence and incarceration with realism and compassion. Those are just a few of the rare and admirable aspects of the Sundance drama, but its biggest accomplishment may be that it remains so grounded and clear-eyed while being, at times, more a state of mind than a TV show.

“What we were always trying to do is allow the viewer to feel that emotion and cry for us, and not force it on them,” Crawford says. “Let them want us to cry, and let them feel the sadness. I think that takes a very sophisticated audience, and I think we knew what we had in Sundance. [We could focus on] the subtleties of the performance. Rarely do you get to let those kind of shine through unless you’re doing a little indie film or something like that. You know, a lot of times that stuff just gets all cut to pieces in editing. But Ray [would say], ‘I want to sit. I want to hold on to this [moment where the character is thinking.] ‘Now what? You’ve got all that information — now what are you going to do with it?'”

In the season premiere, Young displays his character’s pain and self-doubt with his usual devastating honesty; the rawness and subtlety of Young’s performance has been one of the finest elements of “Rectify.” And as far as the actor is concerned, Daniel must do much more than merely hold down a job and go through the motions of daily life.

As Young notes, Daniel was supposed to be dead — he spent years on Death Row rarely even seeing another person’s face. But he’s not dead, so what does he do with that?

“The question, in many ways,” Young says, “is about having to re-educate himself toward acceptance.”

The cast of “Rectify” is unusual, not just because they are all very talented; I’ve rarely spoken to a group of actors who have thought so long and hard about the ethical and spiritual issues at the core of their show.

“They’re all fierce individuals and that’s why I was attracted to them. But good Lord, it’s like trying to herd cats and the king cat is in charge,” says McKinnon with a laugh. But he gets it: He is an actor himself, and he understands how important it is to give actors the space they need to find honest moments. Just as McKinnon’s patience paid off, in the form of vulnerable and moving television, any audience member willing to embrace “Rectify’s” measured pace and quietly empathic storytelling will be in for a very rewarding experience. (The first three seasons are on Netflix, should you feel an urge to catch up.)

Another of the show’s core accomplishments has been the way it’s depicted an array of experiences and moments, some light and some heavy, without ever losing track of where the story is going. It has been a hard journey for Daniel and his family, but, at times, it’s a funny, surreal and sweet one as well (the entire cast excels at very dry, deadpan comedy).

That generous spirit is another quality that makes “Rectify” emblematic of this messy, curious, and exhilarating era in television. If there’s one idea that unites many of the most exciting shows around right now, it’s a shaggy and strange form of hope. So many of today’s best shows eschew nihilism and embrace the idea that, no matter how hard life is, hope and joy could be around any corner.

I haven’t seen the “Rectify” series finale, but I don’t need to have seen it to know that it will be suffused with pain, hope, kindness and wonder, and to be sure that I’m very likely to cry before it’s over.

“We all know we’re going to die, and yet we have a sense of optimism,” McKinnon says. “And I think that’s what continues to be uplifting about the human condition — that in spite of … the struggles of life, we’re also able to find the unbearable lightness of being alive. Our characters, as they go on the journey in the last season, at times will find that optimism of going forward. So when we leave them, perhaps that will be part of what we take with us: that they’re not all pessimistic about life.”

Ray McKinnon also addressed the final season of “Rectify” at a recent NYTF panel, which Variety’s Cynthia Littleton covered.