Set among the events surrounding Martin Luther King's assassination, Peggy tries to get a new apartment, Ginsberg is set up on a date, and Don has a revelation during his weekend with the kids.

As the firm prepares to go public, Don and Pete's actions cause them to lose two huge clients. However, Roger uses a new connection to put them in position to gain their biggest client ever.

Things quickly become awkward after the two firms merge, Don asserts his dominance over Sylvia, Pete has to deal with his ailing mother, and Bob Benson helps out a sick Joan.

The creative department has a wild, drug-influenced weekend as they work on the Chevy account, Don has trouble letting go of Sylvia, and Sally walks in on an unwelcome intruder.

Cutler and Chaough prepare to make radical changes to the firm while Sterling and Draper are visiting a client in Los Angeles. Joan's decision to go after a new account on her own leaves Pete furious and frustrated.

Don is preoccupied with keeping Sylvia's son from being drafted, Peggy has a rat in her apartment, Don and Ted bury the hatchet, Pete has a problem with his mother's new nurse, and Sally makes an accidental discovery about her father.

Don renews his battle with Ted after seeing his relationship with Peggy, Sally interviews at a boarding school, and Pete discovers Bob Benson's background.

With his personal and professional life crumbling around him, Don positions himself for a change of scenery. Meanwhile, Pete's life is falling apart as well, thanks to the meddling of Bob Benson.

Don is on the outside looking in on the forced indefinite paid leave from his job. While Ted heads back to New York for a few days, Don takes the opportunity to head to Los Angeles in part to meet with a California transformed Pete while he reunites with Megan, who is living full time there while pursuing what looks to be a promising acting career. Back in New York, Peggy avoids Ted at all cost while she learns to deal with the new "Don", Lou Avery, most specifically on the Accutron account for which she is getting consulting help from Freddie Rumsen. On top of that, she is also having to deal with being a landlady to who she believes are overly demanding tenants. Ken feeling overworked leads to Joan taking over his scheduled business meeting with Wayne Barnes, the new Head of Marketing for Butler Footwear. Barnes' news results in Joan taking what she hopes will be seen as decisive and preemptive action in overcoming a potential problem, action which she hopes demonstrates that she deserves to be more than just a glorified secretary. And Roger meets with Margaret on her request, the two who have been somewhat estranged over the last few months. Their individual new approaches to life may result in a friction-free reunion.

Sally discovers that Don is not working, Pete lands a big account but is undercut by management, and Joan is forced to move some secretaries around after Lou and Peggy have some problems.

After a fight with Megan during a surprise trip to California, Don decides it's time to get back to work. Meanwhile, Betty joins Bobby on a field trip to a farm.

Don returns to work, but quickly falls off the wagon after learning that he's been assigned to Peggy. Meanwhile, Roger and his ex-wife go to a commune to rescue their daughter, who has abandoned her child.

While Lou becomes the object of ridicule for the copy writers, Don tries to get away to California after a call from his pregnant niece. Meanwhile, the new office computer drives Ginsberg to the brink of insanity.

Peggy has second thoughts about her Burger Chef campaign when Don is asked to pitch her commercial, Pete visits his wife and daughter on his trip back to New York, and Bob Benson gets some surprising news from G.M. about the account.

Don and Peggy prepare to pitch to Burger Chef, one day after the Apollo Moon Landing. Meanwhile, a power struggle in the firm between Sterling and Cutler leaves Don's future hanging in the balance.