The returning drama premieres Sunday, Oct. 13 at 9 p.m. on AMC

By Dalton Ross
September 13, 2013 at 04:00 AM EDT

Andrew Lincoln is stabbing the head of a zombie over and over again. The man is showing no mercy whatsoever. The odd thing is, Lincoln has no knife. Instead, he is slicing the air with an imaginary blade. Uh-oh, has Rick Grimes gone off the reservation again? Have his delusions returned? No — in fact there is a method to his madness. Lincoln is using this rehearsal time on The Walking Dead‘s Atlanta prison set to hone the tricky maneuver of dropping his real machete and then stabbing with an imaginary one that will be digitally added later for maximum visual terror.

After dealing with the physical prep — which includes having lots of blood sprayed and smeared all over his body — Lincoln must prepare mentally for a scene that will find Rick and son Carl navigating through a minefield of the undead. ”I need to go get emotional,” says Lincoln, traversing a sea of 61 zombie extras, crew members carrying zombie dummies on their backs, and costars like Norman Reedus (who is busy handing out Rolos) to find a spot all his own.

Lincoln puts in his earbuds and cues up some heavy metal. He immediately drops to his knees, sways back and forth, and then doubles over, pounding the concrete with his right fist. Whatever is happening here at the prison in season 4 of The Walking Dead, it is definitely not good. The survivors will have to deal with a dramatic increase in the number of attacking flesh-eaters, but also a mysterious new threat that will strike them unexpectedly. ”Mother Nature herself is actually closing in on these people,” teases exec producer Robert Kirkman. Here’s what else you can expect:

Rick Grimes, Andrew Lincoln
When the action picks up in season 4 several months later, a council will be making all the important decisions for the newly expanded group at the prison, but former leader Rick will not be a part of it. So what is Rick up to? ”He’s farming!” says Lincoln. ”He’s decided to renounce the brutality of the world for the sake of his son and infant daughter. It’s almost like he’s a guy who’s suppressing a side of himself in order to bring up his children as best as he can.” Adds Chandler Riggs, who plays Rick’s son, Carl, ”His dad wants him to be a kid now. So he gives it a fair try.”

The Governor, David Morrissey
No character devolved last season more than the Governor, who began as a charismatic town hero but by the end was gunning down his own people just for the heck of it. While producers will not reveal when or how he will return, Morrissey says not to expect a kinder, gentler creature. ”He isn’t the man he was at the start of season 3. He’s the man at the end of season 3, so I’ve got to be true to that man. It’s the man he’s become.”

Glenn & Maggie, Steven Yeun & Lauren Cohan
It got a bit rocky for the couple last season after the Governor assaulted Maggie, but things are on the upswing for the now-engaged pair. ”They’re happier. They have their own room!” says Cohan of their new cell in C block. ”Glenn and Maggie have a joyful relationship,” adds Yeun. ”But the problem is that the conditions of this world scare Glenn.” Whereas Maggie will embrace the live-life-to-the-fullest-while-you’re-still-among-the-living philosophy, Glenn is desperate to protect what they have, and that will lead to what Cohan describes as ”push and pull.”

Daryl Dixon, Norman Reedus
Reedus says he’s pretty much asked on a daily basis about Daryl’s (lack of a) love life. After all, Rick, Lori, Shane, Andrea, Glenn, Maggie, and even the Governor have all found romance on the show. So will the resident badass with a heart of gold finally get some lovin’ in season 4, perhaps with Melissa McBride’s Carol? ”I don’t think he’s emotionally equipped to handle that yet,” says Reedus. ”I’ve been fighting having a love interest the whole time. It just seems too easy. I don’t want him to have any sort of experience in that area, really. So when it happens, it’ll be a big deal.”

Bob Stookey, Lawrence Gilliard Jr.
The newest addition to the group is a bit of an enigma. ”My character appears a week after he’s been at the prison, and so you really don’t know anything about him,” says Gilliard of the former Army medic, ”just that Daryl found him out in the woods.” While working toward the future, Stookey must learn to put aside the horrors of his past: ”He feels a bit cursed.”

Sasha & Tyreese, Sonequa Martin-Green & Chad L. Coleman
”Sasha and Tyreese were very integral in bringing the whole Woodbury community to the prison,” says Martin-Green, ”and now it’s all about building it.” But that doesn’t mean that Tyreese is at ease in his new role in this postapocalyptic society. ”He’s feeling uncomfortable,” says Coleman, ”and is still trying to find his place and how he can be of service to the group.”

Hershel Greene, Scott Wilson
Wilson is digging the ”frontier setting” of the prison. ”They’re growing their own vegetables. They have their own livestock. So to me that’s a positive sign,” he says, before adding, ”Of course, how long can that last?” You can expect more from the farmer/vet than just nuggets of wisdom. ”He’s handicapped, but he’s a vital person. So they are using his handicap in a more active way than they were last year.”

Michonne, Danai Gurira
You can bet that the katana-sword-wielding warrior will not rest easy until the Governor (who killed her BFF Andrea) is put down. ”The word about Michonne this season is ‘obsessed,”’ says exec producer Robert Kirkman. ”Minute one in season 4 she is on the hunt, and it doesn’t look like she’s gonna be giving up anytime soon.” And although Michonne — who will see plenty of action while riding her new horse, Flame — will be more integrated into the group, according to Gurira, ”the idea of embracing a whole community is still something very uncomfortable for her.”