Don has to deal with issues between a TV comedian and his wife; Joan finds Don the perfect secretary.

The writers make an attempt to stave off late-night boredom during a mandatory overtime session. Roger throws a party as Joan and Greg host their own party. Sally has a run-in with Grandpa.

A former client makes a return; Betty and her kids go on a trip; and Joan and Greg make plans for their future.

Don takes a trip. Joan has scheduling problems. Don and Lane get to know each other a little better.

A deadline disrupts Sterling Cooper Draper Pryce.

For the Draper family, life has changed. The children must adapt to a new home, a new brother, and a new stepmother. Don seems to have everything a man could want. However, Megan, still employed at the agency, has difficulty interpreting Don's expectations for a sex kitten at home and a prim and proper employee at the office.

Don and Megan work out some of their issues, Roger and Pete butt heads, and Joan has a run-in with a house guest.

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.

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.

Roger pawns off a project on Don, Joan goes on a business trip and Peggy and Pete cannot agree on how to deal with an account.