Over three celebrated seasons, AMC's Mad Men piled up the glittery awards and critical plaudits, so it's not as if the show needed a drastic shake-up to raise its profile. Don't mess with something that isn't broken, right?
But a shake-up is exactly what creator and executive producer Matthew Weiner delivered in season three's tumultuous finale.
Issuing a bold declaration of independence, ad man Don Draper (Jon Hamm) and some of his most loyal colleagues bolted British-owned Sterling Cooper to start their own company. Meanwhile, Don's marriage disintegrated as his wife, Betty (January Jones), filed for a divorce and fled town with another man.
Now, as season four of the moody period drama unfolds, there's so much change in the air that some cast members liken Sunday night's opener to a new pilot episode. Weiner, however, says it feels more like a spin-off.
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"We've got our established characters, familiar faces, but it's a completely new dynamic," he says.
And much like Don's advertising companions, who appear to be invigorated by their fresh status as scrappy underdogs, there is a sense of rejuvenation among the Mad Men ensemble.
"It's exciting," says Elisabeth Moss, who plays enigmatic copywriter Peggy Olson. "We're all charged up. It feels like there are no rules anymore. Anything goes."
That excitement, however, was preceded by plenty of anxiety and apprehension. It's not often, after all, that a beloved, highly decorated show attempts such a radical makeover.
"In some ways, it felt very risky and terrifying," Weiner says. "While shooting last season's final scene (in the Mad Men office), I looked at one of our writers and said, 'What am I doing? I could have just painted the place.'"
Notoriously tight-lipped, the Mad Men principals aren't about to reveal many details for a season that appears to focus on consequences and identity. (AMC made only Sunday night's opener available for preview.)
"The characters are coming to grips with what they've done," Moss says. "They're dealing with past mistakes and discovering who they really are. They're trying to move on."
But moving on doesn't come without some emotional pain. As the season opens, Don is living alone in a gloomy Greenwich Village apartment and engaging in awkward blind dates. He misses his kids — and much of the idealistic life he so carefully created and strived to live up to.
"A good deal of Don is uncentered and spiritually lost," Hamm recently told TV Guide. "He's going to have to confront this maelstrom."
As for Betty, she appears to be developing into a tragic figure. Fed up with Don's lies and infidelity, she impulsively ran off with Henry Francis (Christopher Stanley), an older man and aide to Nelson Rockefeller. But it isn't clear whether she's any happier or any closer to knowing who she is.
Weiner says he thought he and his collaborators made it emphatically obvious in the third-season finale that Don and Betty had finally gone bust. He was surprised to hear from so many viewers during the offseason who yearned for reconciliation.
"People still ask me, 'What's going to happen with the marriage?'" Weiner says. "I've been mystified by the fans who say they still want them together. It was one of the worst marriages ever!"
Still, other fans — and many critics — are relieved by the breakup. If there was a predominant complaint about season three, it was that the show spent too much time in the turbulent Draper household and not enough at the workplace, where Mad Men really made its mark with insightful glimpses into 1960s-style office politics.
On that front, things are changing as well. No longer dominant forces in the Manhattan ad world, Don and his crew have to scratch, claw and resort to publicity stunts to drum up business.
Under this scenario, the fledgling enterprise, Sterling Cooper Draper Pryce, must be more savvy and agile. And as the old way of doing things becomes obsolete, it's apparent that the younger execs, including Pete Campbell (Vincent Kartheiser) and Peggy, will have a greater impact.
Mad Men earned two straight best drama Emmy Awards and could make it three straight next month, when the trophies are handed out. For season three, the show nabbed 17 Emmy nominations, including bids for Hamm, Jones, Moss, John Slattery and Christina Hendricks. Still, Moss insists there will be no coasting.
"People might think that we're more comfortable now, but it's so not like that," she says. "We feel so much pressure to keep the standards up and not disappoint anyone. Every year, we try to meet that pressure head-on and tackle it."