The simmering tension will include last season's bombshell of a story line about Don's true identity: The guy born Dick Whitman stole a dead man's name during the Korean War and reinvented himself as Donald Draper. (When Pete uncovered this secret, he unsuccessfully tried to blackmail his boss into promoting him.) ''Here's the issue: Don Draper's doing great. Dick Whitman, not so,'' Weiner explains. ''And we shouldn't stop worrying about Don being discovered. His wife doesn't know. Will she find out? Does it matter? There's also this whole chunk of his life that we don't know about.'' If last year's arc showed Betty slowly becoming angry at Don's infidelities, at being imprisoned in the gilded cage of housewifery this season ''her energy's going in different places,'' Weiner says. But he warns, ''Don't expect to see her holding a picket sign and burning her bra.'' Recovered from his two heart attacks, Don's mentor Roger is back full-time. As for Peggy, she will excel in her new position of junior copywriter. (Inquiring fans still want to know: How could Peggy have been unaware she was with child until delivery? Answers Weiner, ''People say, 'Peggy's so smart!' But the truth is she's 20 years old. She knew and denied it. She put it out of her mind.'') Pete keeps trying to climb the corporate ladder, but whether or not he knows he's the father of Peggy's baby is a question that no one is willing to answer. ''I cannot say,'' Moss, 25, says with an apologetic giggle. ''If I did, I'd be dragged out of here by my ponytail!'' Kartheiser, 29, is no help either, offering only a mock-incredulous response: ''I can't believe you're actually coming to our set and trying to get juice out of us.''
The subject of Peggy and the fate of her baby became the show's most fiercely guarded secret after spoilers found their way onto the Internet in April. ''At our second table read, Matt really laid into everyone,'' says Christina Hendricks, 30, whose Joan Holloway is the haughty queen bee of the Sterling Cooper steno pool. ''He was like, 'Do not tell your friends! Do not tell your boyfriends! Do not tell your agents!' He put the fear of God in us.'' Clearly, Weiner has taken a lesson from The Sopranos creator David Chase in adopting the art of plotline omertà. At the briefest mention of the leak, the Mad Men boss launches into a tirade. ''I can't believe that anyone could truly love the show and tell someone else what happens on it. That's what kills me,'' he says, shaking his head. ''They are ruining the show that they love. Why do people want to know the story? Why can't they just sit back and be entertained?''
NEXT PAGE: ''We know it's a good script when we do our table read and the heads lower, like, five times. I definitely cringe at the sexist things the guys say. The guys cringe too.''