Andrew Lincoln Andrew Lincoln

[Warning: The following story contains spoilers from the Season 2 premiere of The Walking Dead. Read at your own risk.]

"I hear we're getting shot," says an actress, smiling behind a mask of rotted teeth. "Awesome!" replies a bloody actor with an enthusiasm that's, ironically, everywhere on The Walking Dead set — from undead extras to lead actors — even after an in-house summer shake-up.

"It's jam-packed, character-wise and action-wise," says Andrew Lincoln, as electrified by the world of hungry corpses as his character, Rick, is terrorized by them. Deeper, darker and (at 13 episodes) more than twice as long as last year, Season 2 of the record-breaking AMC drama questions the cost of survival, and how much humanity its characters can salvage. Executive producer Robert Kirkman, author of the original comic book, promises "gut-wrenching drama." And, of course, lots of guts, too.

This season's opener started with a shock — young Sophia got lost in the zombie-filled woods — and ended with a bang, as Rick's young son, Carl, was accidentally shot. "They're the hope of the future," says Steven Yeun (Glenn). "If the kids are gone, what's the point?"

Not everyone shares this concern. "Some just want to keep moving, others are desperate to find Sophia, and everyone has their own agenda," says Melissa McBride, who plays Carol, Sophia's mother. Adds Kirkman, "It's interesting how quickly a few move to self-preservation. It'll shock you who goes there, that 'we need to make sacrifices' mode."

That philosophical split will cause tension between best friends Rick and Shane (Jon Bernthal). "Shane figures out what it takes to survive: a lack of empathy and emotion," says Bernthal, whereas Rick tries to hold onto his humanity — to a point. "Not that Rick's gone to the dark side," says Lincoln, "but that's the question: Can we survive without becoming monsters? And everyone's arguments are sound. One week you're going, 'Shane is a psycho!' and the next you're like, 'But he's right!'"

Caught between the two men is Lori (Sarah Wayne Callies), Rick's wife — and Shane's ex-lover. "Every time Rick says, 'We have to be human,' Lori hears that," says Callies, "but every time Shane says, 'Guys, it's math. It's what we need to do to keep Carl alive,' that makes sense, too."

It's a dynamic, Kirkman says, that'll make it even harder to keep Lori and Shane's Season 1 affair secret: "Carl's shooting brings them into new areas, puts a lot of strain on Lori and Shane, and brings up some dark stuff they've been keeping under wraps, so to speak."

Could Lori's condition, like her comic-book counterpart, become even more delicate this season? (Spoiler alert: The character was revealed to be pregnant in the comic book.) Callies will only say Lori's focus is Sophia and Carl, but adds vaguely, "Later, she may have some decisions about taking on new responsibilities."

What else can we expect this season? Dr. Jenner's secret, whispered to Rick in the final moments of last year's finale, "will be revealed," says exec producer Gale Anne Hurd. Andrea (Laurie Holden), the most broken survivor after her sister's death, will morph into a more powerful player. "I've been off with the boys — learning to shoot, embracing my inner tomboy," says Holden. And Glenn makes a connection with a new character, Maggie Green (Lauren Cohan). "It gives him someone to live for," says Yeun.

For more on The Walking Dead, pick up this week's Halloween preview issue of TV Guide Magazine, on newsstands Thursday, October 20!

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