Don Draper is the creative director at Sterling Cooper, a Madison Avenue advertising agency. Don takes the lead on the firm's biggest accounts such as Lucky Strike. When the trade commission cracked down on tobacco health claims, he struggles to keep the Lucky Strike cigarette account from leaving the agency. He finds solace in the arms of the rebellious artist Midge -- instead of his beautiful wife Betty.
None the wiser, Betty supports her successful husband and raises their two children in the suburbs of New York. Her life might seem the picture of perfection until an odd condition in which her hands go numb leads her to crash her car and opt to see a psychiatrist, a taboo concept in the conservative Draper household.
Betty isn’t the only woman struggling. Don’s new secretary, Peggy Olson, gets a crash course in office politics from head secretary Joan, a fire-engine redhead with attitude and the perfect hourglass figure. Joan recommends succeeding in the “boy’s club” by showing a little leg, encourages her not to be overwhelmed by the typewriter’s technology and offers her a doctor who prescribes contraceptives to unmarried women.
This “boy’s club” is led by up-and-comer Pete Campbell. He is on the verge of getting married, but that doesn’t stop him from being an insatiable flirt. Don even offers Pete man-to-man advice about how his playboy escapades will make it hard to climb the ladder. “You’ll die in that corner office, a midlevel exec with a little bit of hair who women go home with out of pity.” Still, when he sets his sights on Peggy, he won’t stop until he sleeps with her.
After putting out the fire with Lucky Strike, Don turns to a new account -- a Jewish-owned department store in Manhattan. Surprised to find a woman at the other end of the table – along with David Coen, a token Jewish employee from the mailroom – Don has little patience for Rachel Menken’s demands to turn her store into the next Chanel nor her distaste for his less-than-innovative idea to offer coupons to housewives. A private meeting over drinks, however, starts a romance that neither Don nor Rachel can control.
When Pete returns from his honeymoon, he truly believes he can be faithful, but it’s not long before he and Peggy have another romp in his office. After he makes a cutting remark at an office party, Peggy discovers that nearly every man in the office -- even the ad execs Paul, Ken and Harry -- sees her as merely a skirt.
The only exception is Salvatore, the Italian art director. He opts for a dinner with Elliot, a sales rep for one of Sterling Cooper’s accounts -- even when the beautiful switchboard operator Lois flirts with him -- but he’s still too nervous to take things to the next level.
Ken writes a short story that gets published in Atlantic Monthly, which makes Pete so jealous that he resorts to asking his wife Trudy to call in a favor from her publisher ex-boyfriend to get his own story in a magazine. Unfortunately, his is only good enough for Boy’s Life.
In time, Peggy also discovers a talent for copywriting when she takes part in a brainstorming exercise for the Belle Jolie lipstick account. Her shining moment comes when she calls a trashcan full of blotted tissues a “basket of kisses.” Her talent, and the fact that she has been filling out her unattractive dresses lately, make her the perfect candidate for another account, a panty-shaped weight-loss contraption that has a hidden benefit that makes women feel, well, fabulous.
Back at the Draper house, Betty and her friend Francine gossip about their new neighbor Helen Bishop, a divorcee with a 9-year-old son and a baby girl. Betty tries to be open to Helen’s friendship, and when Helen asks her to babysit her son Glen, she obliges. When Helen finds out that Betty has allowed Glen to keep a lock of her hair, however, Helen is disturbed. “What’s wrong with you?” she asks. Betty slaps Helen in retaliation.
Betty's problems deepen when Don is courted by Jim Hobart, an ad exec at McCann, who believes Don could get a higher salary and an international network of clients that include Pan Am and Esso. Determined, Jim even offers Betty -- the vision of Grace Kelly -- a modeling job for their Coca-Cola campaign. She accepts, eager to return to her former life as a working model, but when Don declines the job, she’s pulled from the gig and forced to return to life as a bored housewife.
Don, skeptical of the effects of her therapy sessions, calls Dr. Wayne. “After hundreds of dollars, all you’ve managed to do was make her more unhappy,” he says. Dr. Wayne suggests even more therapy for Betty.
At Sterling Cooper, the firm's partners Betram Cooper and Roger Sterling ask Don to consider working on the presidential campaign in support of a young, handsome navy hero named Dick Nixon. They struggle with how to make him appear better than John F. Kennedy. “Kennedy?,” Don says. “Nouveau riche, a recent immigrant who bought his way into Harvard. Nixon is from nothing. Abe Lincoln of California, a self-made man. Kennedy, I see a silver spoon. Nixon, I see myself.” Unfortunately, none of their big ideas help. Nixon, at the last minute of the election, loses.
Roger, a heavy drinker frustrated with his wife and depressed and anorexic daughter Margaret, spends his time away from work in hotel rooms with Joan. “Do you know how unhappy I was before I met you? I was thinking of leaving my wife.” He wants her all to himself, but she insists that her life single-in-the-city lifestyle can’t conform to his every whim. But when Roger suffers a heart attack after canoodling with a model in his office, she is devastated.
With Roger out of the office, Cooper makes Don partner, unaware that Don has been dealing with problems of his own. When Don's younger brother, the blue-collar Adam, shows up at his office calling him Dick Whitman, Don does everything he can to keep his former life a secret, including offering Adam $5,000 in cash to leave New York and never see him again. Apparently, Don’s past -- he was born to a prostitute, and when she died in childbirth, they delivered “Dick” to his father, a mean-spirited drunk, and his wife -- is worth hiding.
It’s not long before Don gets a package from Adam, filled with mementos and photographs of the two, and discovers that his brother hanged himself. Pete gets his hands on the package and tries to use it as leverage to get the now-open Head of Account Services title. So, when Don brings in Herman “Duck” Phillips for consideration, Pete tells Don what he knows -- according to a friend at the defense department, Dick Whitman died in Korea 10 years ago, and a man named Donald Draper dropped off the map. In fact, Don had gone to war to get away from his family, and when his lieutenant died in an explosion, he switched dog tags and returned to America a new man. Don recognizes the attempt at blackmail but doesn’t back down.
Realizing that Midge’s anti-establishment revolutionary personality is far too different than his, Don goes to Rachel with a sudden desire to go to Los Angeles with her for good. Sadly, she realizes that he doesn’t want to run away with her. He just wants to run away.
With no other option, Pete tells Cooper about “Don,” a deserter and criminal. Cooper, to everyone’s amazement, doesn’t care. “This country was built and run by men with worse stories than whatever you’ve imagined here.”
Soon, the ad men’s lives all start to get even more complicated. Pete realizes that he has to use his family’s high-end connections -- like the new acne medication Clearsil --- to get ahead in business. Harry, after a spontaneous tryst with Pete’s secretary Hildy, gets kicked out by his wife and spends his nights sleeping in his office. Even Peggy, realizing her place in society, tries hopelessly to fit in. “Those people in Manhattan?” she says. “They are better than us. They want things they haven’t seen.”
Peggy’s luck begins to change when Don gives her a promotion, a new desk and the Clearasil account. Before she has time to celebrate, however, she grimaces with stomach pain and heads to the doctor. “You didn’t mention that you were expecting,” the doctor says to Peggy’s dismay. That night, a nurse brings a swaddled baby boy to Peggy. She just turns her head away.
Betty, planning for their Thanksgiving trip, is upset to discover Don won’t go. “I don’t understand why you can’t make my family your family,” she says. When she discovers that Francine’s husband is having an affair, she begins to wonder about her own husband. After some investigating, she discovers that Don has been calling her psychiatrist and decides to take control of the situation. At Dr. Wayne’s office, Betty talks about how Don doesn’t have a family and parades affairs in her face. “I can’t help but think that I’d be happy if my husband was faithful to me,” she says.
Meanwhile at Sterling Cooper Don is pitching a campaign to Kodak, a potential new client. They are looking for a promotional angle for their new slide projector. Don makes his presentation using the device. “This is not a spaceship, it’s a time machine,” he says. “It goes backwards and forwards, and it takes us to a place where we ache to go again. It’s not called 'The Wheel,' It’s called ‘The Carousel.’ It lets us travel around and around and back home again.” He concludes with an image of him and Betty kissing on New Year’s. The Kodak clients cancel their meetings with other agencies and sign with Sterling Cooper.
As he rides the train back home to Ossining Don imagines arriving home as Betty and the kids have finished packing for their trip. “I’m coming with you,” Don says. Betty, emotional, watches as he picks up the kids, kissing their heads. When he really does arrive home he arrives to find the house empty. He sits on the steps and holds his head in his hands.