The only constants in the world of AMC's hit show? Zombies swarm, characters die, and showrunners change; season 4 is no exception

[Spoiler Alert!]
Chandler Riggs is not allowed to fire a gun. In fact, he’s not even permitted to carry one. Because he is under 14 years of age, the actor has had to make do with fake rubber firearms whenever his character, Carl Grimes, is called upon to pack some heat. But all of that is about to change. When the clock strikes midnight here on the Senoia, Ga., set of The Walking Dead, it’ll be June 27 and Riggs will officially turn 14. The cast and crew are literally counting down the seconds until the teenager can be officially armed. ”Ten! Nine! Eight! Seven! Six!…” When the chant reaches ”One!” star Andrew Lincoln presents his onscreen son with a special birthday present — an M16 rifle to be used for his very next scene. ”It was so cool because Andy came and he bowed down to me and gave me the rifle like a sword or something,” Riggs recalls later with a huge smile on his face. And what, exactly, did Riggs proceed to do with said rifle? ”We blew some zombie brains out. It was awesome!”

Later that day, Lincoln leads the crew at catering in a rousing rendition of ”Happy Birthday” while bringing out a special M16-shaped cake (last year it was a zombie cake with edible eyeballs). Finally, the teenager’s birthday concludes the same way it began, with the newly armed Riggs laying waste to advancing walkers. ”Action!” yells the director, and Riggs begins squeezing the trigger. RAT-A-TAT-TAT-TAT-TAT goes the gun. After firing off a few rounds of blanks, Riggs reloads, not even missing a beat as he jams another clip into the weapon and fires some more. RAT-A-TAT-TAT-TAT-TAT.

The scene ends, and the cast and crew explode into applause. ”He’s smoother with clips than any of us!” marvels Norman Reedus, who has killed his fair share of zombies as resident badass Daryl Dixon. Riggs chalks his proficiency up to ”a lot of Call of Duty.” As the birthday boy walks back up the prison hill, his long day finally at an end, Reedus salutes him with an enthusiastic high five. ”Good job, Rambo!”

While a teenager getting his hands on a firearm may not be cause for celebration in the real world, the survivors of The Walking Dead need all the crack shots they can get. Because when AMC’s apocalyptic zombie drama returns in mid-October, there will be more zombies. There will be scarier zombies. And there will be a mysterious new threat that will hit the survivors where they least expect it. Of course, season 4’s biggest twist occurred before the season even began filming. Showrunner Glen Mazzara — who replaced show creator Frank Darabont and was credited with ramping up the pace and action when he took over the top spot halfway through production on season 2 — announced in a joint statement with the network last December that he himself would be leaving at the end of season 3 due to ”a difference of opinion about where the show should go moving forward.” This even as ratings continued to climb, with the season 3 finale netting a record-smashing 12.4 million viewers.

Sons of Anarchy showrunner Kurt Sutter — who worked with Mazzara on The Shield and is never shy about expressing an opinion — immediately started blasting both AMC and The Walking Dead comic creator Robert Kirkman (also an EP on the show) in various expletive-filled online posts. While Sutter insinuated it was Kirkman’s influence that resulted in both Darabont’s and Mazzara’s departures, Kirkman waves off that notion. ”It’s very nice for people to assume that I have far more power than I actually do,” he responds. ”The Kurt Sutter thing was funny, because on one hand, I’m this silly comic-book writer that doesn’t know what I’m doing. And on the other hand, I’m this Machiavellian genius — this hatchet man that’s ruining people’s lives. And that couldn’t be further from the truth. It definitely wasn’t any kind of plot on my part to keep this show in a cycle of showrunners and chewing them up and spitting them out.”

In an effort to minimize the trauma of yet another showrunner change, AMC installed former No. 2 Scott M. Gimple, who’s written some of the series’ most outstanding episodes — including season 2’s ”Pretty Much Dead Already” (in which Sophia was finally discovered during Barnageddon) and last season’s ”Clear” (which saw the return of Lennie James’ mentally compromised Morgan). Naturally, Gimple knows that a lot is riding on his shoulders. ”I love everybody that makes this show, and the fans are unbelievable,” he says. ”There are a whole lot of people that I don’t want to let down. I started reading the comic book when it came out, and I wasn’t on season 1, so I was a fan of the show too. I don’t want to let down myself, either, strictly as a fan.”

Ask any cast member how Gimple’s season 4 will differ from Mazzara’s season 3 and you’re going to get pretty much the exact same answer with the exact same word popping up over and over. ”I think the scripts this season have been really different, intricate, character-driven,” says Lincoln, who plays the show’s lead, Rick Grimes. ”Deeper character development,” responds Lauren Cohan, also known as farmer’s daughter/zombie slayer Maggie. ”A lot of character development going on, really rich character development,” offers Chad L. Coleman, who joined last season as bighearted big man Tyreese. ”A great melding of character and action,” replies Danai Gurira while casually twirling one of Michonne’s training swords. Even Kirkman himself can’t help but get into the act: ”I think more than anything Scott is a character guy.” You don’t say!

So what does all this ”character” stuff mean for the show? While last season’s almost nonstop wall-to-wall action was a welcome change of pace after the slow burn of season 2 — Anyone seen Sophia? Anyone? Bueller? — expect the return of some quieter moments. ”People might complain about season 2, and people might love the constant motion that happened in season 3,” says Steven Yeun, who plays pizza delivery boy-turned-loverboy Glenn. ”But I think season 4 will be a very good balance and a very good tastemaking year for what the show’s potential is — a beautiful tale of survival that wraps around specific characters, but then also shows you the terror and the doom of a wider scope of horrible society. If that requires a slower pace here and a wider lens there, I think that’s completely fair.” In other words, those quieter moments will only make the impact even more forceful when everything ultimately goes horribly wrong. As Kirkman explains, ”You’ll care about these characters a lot more. So you’ll be all the more upset when they all die.”

Things won’t look that grim when season 4 picks up. But they will look different. Very different. You notice it the first time you walk on The Walking Dead‘s prison set. Everything looks so damn…green. That’s because the jail is now home to a thriving fruit and vegetable garden. Strawberries, pumpkins, radishes, and tomatoes grow in the yard where mountains of file cabinets and broken computer monitors used to pile up. ”We have fantastic greens people,” explains exec producer Gale Anne Hurd of the real food growing here. ”We try to keep the crew and cast from stealing too much.” (Judging by the ”Always shut the gate. The deer are eating our set!” sign that hangs around the corner, it would seem humans are not the only thieves milling about.)

This is far from the only dramatic change to the prison set from last year. A makeshift stable houses Michonne’s new horse, Flame. An outdoor kitchen has been constructed next to the basketball court, and an electric shed featuring an engine generator and numerous extension cords has brought power throughout the prison. The addition of 50 Woodbury residents at the end of season 3 and other newcomers in the several months since is reflected everywhere you look, including the homemade tetherball rig and adolescent drawings of dinosaurs, flowers, and butterflies on an outside wall. A new community has been built here, but it is not one being led by Rick Grimes, who has pulled back to focus more on his son, Carl, and baby daughter, Judith. ”He’s become Farmer Rick!” says Lincoln with a laugh. ”I’m hanging with the pigs. I had one day when I was covered in pig s—, had flies all around my crotch, and blood. Nobody sat next to me — I was like Pig-Pen!”

With the Ricktatorship gone, a new council has been formed among all the factions residing in the prison to make the important decisions. And anyone seeking entry into this community must answer three questions: ”How many walkers have you killed? How many people have you killed? And why?” says Lincoln. ”And if you pass those three questions, you become part of the community.” One person who passes the test is Bob Stookey, a character from the comic book now played by The Wire‘s Lawrence Gilliard Jr. A former Army medic with issues, Bob does not come from Woodbury as in the comic, but rather is found by Daryl. ”You can see there’s something deeper and darker going on with this character,” teases Gilliard. But even as the numbers inside the prison are swelling, they’re nothing compared with the growing ranks of the undead. While season 3 focused more on the human threat of the Governor (David Morrissey), in season 4 the zombies are back and scarier than ever — and they’ve found strength in numbers.

”The walkers just keep coming in larger and larger droves,” says Sonequa Martin-Green, who plays Tyreese’s sister, Sasha. And more walkers mean more zombie extras. ”The first episode, we had days where there were 150 walkers,” brags exec producer and zombie-makeup guru Greg Nicotero while surrounded by the monster action figures that populate his on-set office. ”It was just a massive number.” (One hundred and seventy-nine, to be exact, on the season’s second day of shooting.) Nicotero also has some new toys at his disposal this season, including animatronic puppet zombies with lips that actually peel back. ”There’s some pretty horrible stuff,” says Gimple with a mixture of dread and delight. ”Some very scary stuff. Some imagery that is highly unpleasant in an awesome way. A non-frightening zombie is a lame zombie.”

As if dealing with an increasing number of biters from the outside isn’t enough, our survivors will have a new internal threat to contend with. Producers are mum on specifics, but it’s a threat that will illustrate that ”nature is just as dangerous as the walkers and fellow humans,” hints Hurd. ”The new threat is something you can’t just stab in the face,” adds Gimple. ”You can’t talk sense into it. You can’t make a truce with it. It’s beyond all that. It would be a threat in any world, but in this world it is much more terrifying.” And just in case you thought the survivors were free of the Governor, think again. He will indeed be back in season 4, but not necessarily when or how you expect. ”It’s very much a handover from where we left off in season 3,” explains Morrissey of his character’s current revenge-fueled mental state. ”It’s about him dealing with the man he is now.”

With more zombies and more threats, the biggest question heading into season 4 is How many more characters can this series afford to kill off? Season 3 was a bloodbath, as four different people who had been part of the show from the beginning — Lori, T-Dog, Merle, and Andrea — were offed, as were a slew of newer characters such as Axel and Milton. The good news is that the same thing will not happen again. The bad news is that it could be even worse. ”We will not get rid of four major characters in season 4,” says Kirkman. ”Because we have to keep things off balance. It has to be different every season. Maybe we’ll kill two, maybe we’ll kill 10. Who knows? But it will be different.”

Not surprisingly, the actors who work on The Walking Dead do not enjoy seeing their costars sent to the afterlife. ”If you asked me, I wouldn’t have killed any of them because I’m a fan of every one of them,” says Scott Wilson, who plays former veterinarian/farmer Hershel Greene. ”Truly I miss them.” Watching his TV family be ripped apart may be the most difficult for young Chandler Riggs. ”It’s really hard to deal with because you see them every day,” says the teen. ”You get to be really good friends with them, and then you never really see them again. It’s sad.”

Newcomer Gilliard has particular experience in this department, as his character D’Angelo Barksdale was killed off during season 2 of The Wire. ”I really don’t dig that part of TV nowadays,” he admits while waiting out a rainstorm in his trailer. ”Personally, I think this is unfair to the actors because we’ve got lives. We’ve got families and we should know if we’re going to have a job next week…. Because of that, it makes it hard for me — and I think for a lot of actors — to give a hundred percent when you feel like any week you could be killed. So why am I busting my ass when I don’t know what’s going to happen?”

Beyond any offscreen issues the cast may have to endure when characters are eaten by members of the undead, there is also the onscreen impact it has on the show and the fans. ”I hate it when one of the OGs goes,” says Reedus in his trailer while cradling a shotgun that may or may not be real. ”It really bums me out. It’s taken three seasons for people to get wrapped up in certain characters. I think once you invest in those characters, to have them go is just like, ‘Ah, man.”’ Lincoln concurs: ”The more you lose the originals, I think there probably is a breaking point where you irrevocably change the culture of the show.” That change can become magnified if newer characters are also being disposed of prematurely. ”If you don’t give time for people to grow into the show, then it is a concern,” continues Lincoln. ”Axel was a great character. Damn, it was an amazing death, but I don’t know, I’m not in charge of this thing. It’s a tough job.”

Producers defend the character carnage as a means of maintaining realism and establishing stakes. ”You do what’s best for the story, first and foremost,” says Gimple. ”It’s scary to lose characters and a tool in your toolbox, but so much of what we do on this show is about loss…. I mean, that’s just an intrinsic part of this world. That’s never going to change.” The new man in charge then pauses. ”Except in episode 2, when the zombie apocalypse is solved.” Okay, then! Show over! ”Well, no, we keep going. But things take a big turn.” He’s kidding…we think.

Where We Left the Dead
A quick catch-up on the state of affairs when last we saw our survivors

Tough Times for Grimes
Rick (Andrew Lincoln) went cuckoo after his wife, Lori (Sarah Wayne Callies), died during childbirth, though he rebounded thanks to a run-in with old pal Morgan (Lennie James). Meanwhile, son Carl (Chandler Riggs) tapped into his killer side after shooting a surrendering Woodbury teen named Jody.

The Governor’s Gone…For Now
After a failed assault on the prison, the Governor (David Morrissey) gunned down his fellow Woodburyites and then drove off to who-knows-where with his remaining henchmen. (He will return in season 4… at some point.)

Population Explosion
With the Governor in the wind, Rick collected the 50 Woodbury survivors and brought them back to the prison for care and protection. But what remained a total unknown: how these two well-established communities would handle merging into one.

Love in the Time of Walkers
For a show filled with fighting, there still seems to be plenty of time for googly eyes. We look at who will — and won’t — be hooking up in season 4

Glenn & Maggie
Glenn (Steven Yeun) and Maggie (Lauren Cohan) got engaged in the season 3 finale, so where do things stand when the action picks up? ”They have really settled in, and have some semblance of a normal relationship,” says Cohan. ”They don’t have a DVD player, but they have some sleep-filled nights.” There are still challenges, however. Says Yeun, ”I mean, you don’t have a million condoms!”

Daryl & Carol
Shippers have been working overtime trying to get loner Daryl (Norman Reedus) and Carol (Melissa McBride) to hook up, but they may have to wait a bit longer. ”Yeah, they’ve been talking about that since season 1,” says Reedus. ”I think it’s growing into something. I like the slow grow better than just the throw-someone-against-the-tree thing. Never say never, but when it happens, I want it to mean something and not just be a sex scene.”

Tyreese & Sasha
Tyreese (Chad L. Coleman) and Sasha (Sonequa Martin-Green) will definitely not be getting together; although many viewers didn’t realize it, they’re actually siblings! ”Some people thought we were husband and wife,” says Coleman. Martin-Green assures us there will be no such confusion in season 4: ”They are saying it in every scene now. They’re like, ‘Hey, brother!’ ‘Hey, sister, what are you doing?’ They’re going to get it now.”