WHO'S THE FAIREST Mad Men's Hendricks primps for intercourse.

The glorious first season of Mad Men, created by Sopranos coproducer Matthew Weiner, was built around Waspy, hard-playing ad execs on an inevitable crash course with the ’60s—a pride of alpha males led by charismatic, self-created Don Draper (Jon Hamm). But the secretarial pool’s voluptuous queen bee, Joan Holloway, played by Christina Hendricks, proved every bit as fascinating. The character started out exuding sexual confidence, then gradually came to see her assumptions about the world challenged. When Peggy Olson, the new secretary played by Elisabeth Moss (and the show’s ostensible female lead), ascends the corporate ladder based largely on talent and gumption, Joan responds less with jealousy than with befuddlement.

“She’s thinking, Wait! This isn’t how you’ll get a husband,” observes Hendricks, speaking by phone from Los Angeles. The Knoxville, Tennessee, native has had recurring roles on Firefly and ER, and was a regular on the short-lived UPN series Kevin Hill. But the 30-year-old actor knew Mad Men could be more than just another job when she read the script for the pilot. “As an actor, you get so many scripts, and some of them are just so unbelievably bad,” she says. “But when you get one like Mad Men—suddenly you’re like, ‘Hold on!’ All of my friends in town who were actors and actresses were talking about that script.”

And with good reason: The series spreads its insights around liberally, giving each character subtle moments of self-reckoning. One of the first season’s most telling scenes occurred not in Mad Men’s testosterone-soaked central locale, the powerful New York ad agency Sterling Cooper, but in a powder room, where Joan and her roommate, Carol McCardy (Kate Norby), share an intimate conversation. “I feel like I’m stuck somewhere between Doris Day in Pillow Talk and Midnight Lace,” Joan says, primping in a mirror, “and what I need to be is Kim Novak in just about anything.” Carol assures Joan she’s more beautiful than Novak, then confesses her secret love for Joan. While understated, the exchange reveals the show’s dramatic armature: the era’s aspirational culture, nurtured by advertising and movies; its tense yet nuanced sexual politics; and its looming sense of social upheaval.

Mad Men’s much-praised knack for period detail was echoed by Hendricks’s own exhaustive research. She filled the long interval between shooting the pilot and filming the rest of the series by digging into the era’s cinematic touchstones: Alfred Hitchcock films, The Apartment, Days of Wine and Roses. She also looked up a lot of the hit songs of the late ’50s and early ’60s on iTunes, “thinking of what music Joan might listen to.” Another resource was the work of Sex and the Single Girl author Helen Gurley Brown, whom Weiner has credited with inspiring the portrayal of Joan and her coworkers.

Weiner originally had a different vision of Joan, but he revised it after Hendricks read for the part. “I imagined her as a long, lean, slightly older woman, but then Christina came in and I saw her confidence and her sexuality. I thought, This is an interesting person,” he says. Or, as Hendricks puts it, “[Weiner] realized Joan could be more of a courtesan.” The changes paid off: Hypnotically beautiful, the character comes across as both a real, full-blooded presence and a creature of her time.

Mad Men premieres Sun 27 on AMC at 9pm.