When Halt and Catch Fire premiered three years ago, the tech-focused drama was easy to dismiss. It seemed like a garden-variety Mad Men riff, stocked with familiar characters and an unsexy premise—a bunch of geeks trying (and inevitably failing) to invent the future. But as the series enters its fourth and final season, those who initially wrote it off have had the pleasure of seeing themselves proven wrong.

Though Halt and Catch Fire never lit up the Nielsen charts, it’s forged a legacy among critics as perhaps the only worthy successor to the series that launched AMC into the prestige television game, thanks to its careful character development and keen eye for nuance. The show’s tech backdrop is merely a casing for its real engine: complex, nuanced, and strikingly human relationships. After four years, Halt and Catch Fire has shown just how wrong first impressions can be—and how a series can evolve into something wonderful, nuanced, and original.

Season 3 ended on a two-part finale that blasted the show forward four years. In its premiere, Season 4 advances another three years with a cleverly executed office montage. This season’s pot of gold? Halt’s early tech pioneers are attempting to make the fledgling Web searchable.

“We didn’t want to just blow up the frontal lobes of our audience members by jumping again and having it feel wildly different,” co-creator Chris Cantwell says. “So what we chose to do in this time jump was to have them jump three years, but have it feel very much the same—and have the characters feel arrested, almost like they’re frozen. Because technology, at least when it came to the Internet and the World Wide Web, was exactly that. It was frozen.”

Which brings us to Joe in the basement.

Poor ol’ Joe, played by Lee Pace, still isn’t over Cameron (Mackenzie Davis), with whom he hooked up in Season 3—even though she was still married at the time. So while Gordon (Scoot McNairy) builds their company and Cameron phones in her work from Japan—both literally and figuratively—Joe spends all his time in the office basement, scribbling on Post-it notes and obsessing over the idea of indexing all of the pages on the Web. “To just put him in that dungeon was super fun for us,” Cantwell admits. “We really embraced that. The way he looks and the way he acts—he just doesn’t seem great.”

At first blush in Season 1, Joe seemed like a trope we’d seen plenty of times, including on Mad Men: a charismatic, womanizing man whose business prowess is outweighed only by his propensity for brooding. But over time, he’s been incrementally humbled—and perhaps more impressively, all of his character shifts have felt earned. When Joe’s protégé committed suicide—a plot twist that easily could have felt cheap and manipulative—the tragedy deepened viewers’ understanding of Joe’s capacity for sorrow; even after the time jump in the Season 3 finale, he is still shaken by it. As Joe relegates himself to the basement, it’s hard not to wonder whether he has rejected the idea of being the grinning face of yet another company.

“I think Joe kind of sped into our show in a Porsche, and he was this shark who was going to get what he wanted . . . and then we got to see that guy exist in the world, and see that guy confront time,” says co-creator Christopher Rogers. “Big credit to Lee Pace for that. He’s really embodied that guy with a humanity that would have been easy to miss if it was this kind of one-note, sharky salesman-executive-type guy.”

Just don’t worry, Joe MacMillan fans: as messed up as he is, Joe remains both compelling and, yes, dreamy, even in his 90s grunge garb. “I was watching a cut of Episode 7 yesterday, and there’s a shot of him where I actually felt like I should have my own face removed and destroyed,” Cantwell says with a laugh. “Because he’s so good-looking in this shot, I was like, ‘Jesus, it’s amazing.’ And then also he turns around and does an incredible performance.”

Beautiful as Joe’s arc has been, no character transformation has been more central to the show than that of Donna. In the beginning, Kerry Bishé’s character glimmered with potential. She was a capable engineer, but her career had taken a backseat to her husband Gordon’s, as well as her domestic responsibilities as a mother. In Season 2, she and Cameron co-founded Mutiny, which blossomed until it imploded in a dispute that found Donna behaving, to some eyes, like a Machiavellian villain.

Season 4 does nothing to dispense with Donna’s hard-earned toughness; if anything, she’s even more of a boss bitch now than she was before. (Her collection of silk power shirts also makes her Season 4’s best-dressed character.) Neither Bishé nor the show-runners necessarily agree with that “villain” evaluation, though.

“One of the things I love about the show is that the Chrises give all the characters really excellent reasons for behaving the way that they do,” Bishé says. “When it turns out those characters are deeply at odds with each other, it feels satisfying and complex—because there are no villains. There are no heroes.”

Donna and Cameron remain deeply at odds this season, thanks to the explosive ending of Mutiny. Its I.P.O. was a failure, crushing both Donna and Mutiny and driving Donna into the world of venture capital, where she proves to be quite the shark in Season 4.

“She’s really assumed the mantle of ‘she’s the boss,’” Bishé says, “but it still feels like there’s a fundamental thing missing from her sense of herself or her job. . . . That’s what we explore in Season 4. Donna, she looks like she has it all, and in what ways is that true and in what ways is it not?”

“I think Donna is trying to be the boss in the way that she saw Joe be the boss,” Bishé continued. “She wants to be the Joe MacMillan—[but] it doesn’t fit for her.” As the season continues, the actress says, Donna will have to find her own way to lead.

Rogers called Donna’s Season 4 arc “the logical expression of Donna’s great kind of talent and ambition and vision,” but noted that all of the scars from her past—her fights with Gordon; being repeatedly dismissed by the sexist tech industry; and especially her battles with Cameron—have left her very wounded. “We get to see Donna doing what she does so well—but in a lot of ways she’s kind of walled off,” Rogers says. “I think she’s dogged by the insecurities that maybe she’s just a money person that kind of shapes other people’s ideas . . . I think we’ve always endeavored to give both her and Cameron their best arguments at all times. I think they’re equally fallible in the dissolution of Mutiny, and I think sometimes it’s too easy to say a woman who chooses success over being nice is a villain. I don’t know if it’s a characterization you’d hear about the men on this show.”

At first glance, Cameron, too, might seem like a well-worn trope: the punk-rock, sexually liberated woman with the funky haircut. But Mackenzie Davis infuses her character with life and nuance, and Cameron, like all of her friends and colleagues, has changed over time. She will always be an idealist—but in Season 4, time has tempered her once fiery personality. Now Cameron can admit, as all of us must at some point, that she doesn’t really know as much as she thought she did.

Cameron’s relationships are hypocritical, confusing, and, at times, infuriating—in other words, disarmingly human. Joe has betrayed Cameron more often and perhaps more profoundly than anyone in the series, yet she is able to forgive him. Donna is a different story: Cameron just can’t bury the hatchet, largely because she actually trusted Donna.

“I don’t know if Cameron was ever able to fully open up to Joe, and vice versa,” Cantwell says. “I think that the intimacy of their relationship was more rooted in mystique. I think the opposite is true for Donna and Cameron. The two of them grew very close while creating Mutiny in a very healthy way, yet things took a really ugly turn.”

Bishé agreed that the rift between Cameron and Donna “cleaves closer to the heart of both those people.” The Mutiny dissolution, she adds, will always serve as a reminder of their own personal failures. “I think it’s a lot harder to forgive yourself for your own mistakes. And I think that’s what they ultimately need to do in order to come together in whatever way they can,” Bishé says.

Knowing ahead of time that Season 4 would be Halt’s last was a blessing for Rogers and Cantwell: they could end the story on their own terms. Rogers thinks 40 hours was the right amount of time to tell this story without allowing it to grow redundant—and as he says, knowing that this was the final season “opens the playbook. You can kind of do anything in a final season, and you also, get to look back and say, ‘What has this been about ? What questions have we asked? What do we want to answer?’ Or even ‘Do we want to give an answer?’“

“I think the story of this show is a little bit the story of Chris and I learning what it was to have a creative project,” Rogers adds. “We were two guys kind of doing this as our sneaky side project while we worked at Disney when we started this. And then AMC bought it and took us through this kind of looking glass, and we went on this insane odyssey, six years ago when we were both in our late twenties. And now we’re guys in our thirties and we have kids and we’re both married. Somehow, six years have passed, and we’ve known all these people, and gone on this crazy journey.”