WARNING: The following article contains spoilers for The Walking Dead Season 9 episode "Evolution," which premiered Sunday on AMC.

In the months and weeks leading up to The Walking Dead's ninth season, there were almost apologetic promises to return the former AMC powerhouse to its roots. Two seasons of what felt like gratuitous and implausible warfare between the Saviors and the communities had worn audience patience thin, and the steady decline in ratings reflected the frustration viewers felt at the direction the show was taking. Despite that its trajectory largely followed that of the popular comics, show watchers did not rally behind Negan and "All Out War" the way AMC and showrunner Scott Gimple no doubt thought they would.

In hindsight, that makes sense. While Negan and the Saviors made for compelling enemies, their conflict with Rick and the other survivors didn't make for a compelling story -- at least not by Walking Dead standards.  Spending two seasons wrapped around fighting an enemy as obvious and predictable as the Saviors moved too far afield of what made the show so frightening and gripping in the first place: the unknown. But under the skillful stewardship of new showrunner Angela Kang, Season 9 has not only accomplished an incredibly ambitious reset of the show without its anchor character, it's also shifted back to its roots in horror and fear. And the midseason finale, "Evolution," is a shining example of that achievement.

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The episode takes place primarily in Alexandria, the Hilltop and the surrounding wilderness as the communities deal with new members, potential new threats and a confusing uptick in walker herds. Henry's adjustment to the Hilltop is a primary subplot and it's worth noting that, while his journey into young adulthood isn't edge-of-your-seat exciting, it's still more interesting than a story populated with that many new actors has any right to be. The same can be said of Magna's group, and the two new threads continues The Walking Dead's tradition of making us care about new additions in relatively brief time.

Henry's commitment to working with Earl is real, but he's got a crush on Enid. When he sees her making out with former Savior Alden, his poor little heart is bruised, so instead of spending the evening with Earl and Tammy, he skips out on them and gets drunk on moonshine with Hilltop teens. It goes about as well as you'd expect, and he winds up in the drunk tank getting a stern talking-to from his would-be mentor and former alcoholic. Things look optimistic for him, or they would if the end of the episode hadn't introduced a new imminent threat.

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Michonne is also at the Hilltop, and argues with Carol before the "Queen" heads back to the Kingdom about Alexandria's refusal to attend the fair. We don't get more insight into just what happened to break apart the communities, but Michonne is on far better terms with Carol than she is with anyone at the Hilltop, so we do get a better understanding of why she's favoring isolation. She explains to Carol that she'd love for the communities to reunite, but the fact is that they're separate groups with "a whole lot of broken world in between." For whatever reason, Michonne doesn't think it's worth the risk to open up Alexandria to having alliances again -- the solution to what happened between Hilltop and Alexandria can't come fast enough.

At Alexandria, Gabriel is apparently totally responsible for Negan, and the two have what looks to be some kind of warped meditation/therapy arrangement. Jeffrey Dean Morgan and Seth Gilliam still have the chemistry that made them so utterly watchable in Season 8's "The Big Scary U," although that does undoubtedly have something to do with the fact that their characters make for such an odd, but interesting pair. Gabriel is peculiar enough to bring out the genuine side of Negan, and it's clear the relationship has resulted in some growth on the part of the Savior leader who now has nothing but time to work on himself.

As for Gabriel, redeeming the irredeemable remains the only real way he can live with his original sin of locking out all his parishioners and condemning them to death, so his time with Negan, however frustrating, is therapeutic for him, too. Until it isn't, that is. Negan is still Negan, and when he pokes at Gabriel after the priest has learned that Rosita got injured on a mission he sent her on, Gabriel throws up his hands for the day and leaves the cell ... without locking the door. Negan eventually notices and walks out, the happiest we've seen him since he murdered Glenn.

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Finally, in the wilderness surrounding Hilltop, Aaron, Jesus and Daryl spend half the episode wandering through a misty night looking for Eugene. They find him safe, although terrified and injured. He insists the walker herd he and Rosita encountered are not only looking for him, having doubled back to the barn several times while he's waited, they're also communicating with each other. He's panicked, but swears he's not losing his mind, and the others (behaving exactly as members of a post-zombie apocalypse should) don't dismiss him out of hand. To be fair, they've spent the day watching herds circle around each other, double back, ignore sound distractions and in general behave in ways they never have before. So, when Eugene reasons that since the walkers aren't actually dead and do possess a working, however stunted, brain, it makes sense they could evolve and start communicating. It even sounds plausible to us. The fact that he's wrong -- dead wrong, in fact, is part of what makes "Evolution" such an effective episode.

As Aaron and Jesus attempt to drag an injured Eugene to safety, they accidentally trap themselves in an unabashedly spooky graveyard as the "walkers" continue to the stalk them, unabated by traditionally effective deterrents. The men find a gate, but in the time it takes to force it open, they're beset by the dead, and Jesus goes full Jesus to fend them off. The boredom that's built up during his time chained to administration at the Hilltop gets the better of him, and instead of escaping at the first opportunity, he takes the time to kung-fu a few extra walkers ... and in a shocking twist, is killed by a walker who gets the better of him.

It's something we've never seen before on the show, and a moment that breaks apart everything we know, at least for a second. While it looks that way for a terrifying minute, the walkers haven't actually evolved. The herd stalking them was made up of people dressed in walker skins who are inexplicably malevolent. The episode ends with Daryl and the others chasing the strangers away. The climax nails old-school horror and fear the likes of which we haven't seen since the show's earlier seasons when The Walking Dead was more connected to the zombie horror subgenre from which it evolved. If you've read the comics, you know what's coming. If you haven't, congratulations, because this was a reveal on par with Edwin Jenner's whispered revelation to Rick in "TS-19."

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Where "Evolution" really succeeds is in its structure. Kang is proving herself a master at misdirection, distracting us with genuinely compelling subplots in Henry, Negan and the greater discord between the communities before cutting a hard left into this new, mysterious antagonist around whom tension has been building the entire time. The presence of the "whisperers" is felt just on the periphery the entire episode imbuing everything with a sense of foreboding we don't know is there until it's too late. Just as Daryl, Eugene, Aaron and Jesus don't see the true nature of what they're up against until it's literally on top of them, so too is the audience completely in the dark until we see Jesus' jaw-dropping death and the horrific puzzle pieces fall into place.

"What Comes After" employed this tactic to arrive at a hopeful result, distracting us with a spectacular send-off for Rick only to double back at the last second and reveal the actual outcome that had been hiding in plain sight (sort of) the entire time. It was one of the rare, truly optimistic moments in The Walking Dead -- a moment in which the world turns out better than we thought it would. "Evolution" is the flip side of that coin, ending with a world that's more disturbing, demented and frightening than even the survivors of a zombie apocalypse could imagine.  As such, harks back to the bleak, terrifying world the show introduced us to nine years before.

In a weird way, it feels like coming home.

Airing Sundays at 9 p.m. ET/PT on AMC, The Walking Dead stars Norman Reedus, Danai Gurira, Melissa McBride, Alanna Masterson, Josh McDermitt, Christian Serratos, Jeffrey Dean Morgan, Nadia Hilker, Dan Fogler, Angel Theory, Lauren Ridloff and Eleanor Matsuura.