Peggy is going to alienate her family until she is as free as Don.

“The Suitcase” was possibly the best episode “Mad Men” has ever produced — and that’s saying volumes. TKO.

It was a clever-but-not-too-clever way to bring together “the baggage” — unbreakable baggage with secrets locked inside — that Peggy Olson and Don Draper are both carrying in their personal and professional lives.

Peggy is turning into Don’s Anna — as one dies and walks out with her suitcase, the other is reborn on her birthday — even if she doesn’t quite know him as well yet. (But she thinks she does.)

Betty is actually the only one who knows the true Don now, but Peggy would probably take his Dick Whitman news in her usual clipped stride.

I loved their tour of New York during the Liston/Clay fight, even if I cringed at Peggy’s insecure jabs at Don for not sleeping with her. “You’re an attractive girl, Peggy.”

Girl being the operative word there. True, 26 is still very young, as Trudy Campbell said, but you don’t want to be Allison. You also don’t want to be the kind of person who sleeps with Duck, who took a dump (or almost took a dump) in Roger’s office out of spite at Don. You also don’t want to be the kind of person who drinks so much they vomit repeatedly. Just as a tip.

It was a surprisingly touching episode — and so simple! I love “True Blood” and that show also has at least a dozen characters in the works, but they insist on cramming all of their storylines into every episode.

I love that “Mad Men” focuses on just a few people at a time in each episode and gives their stories space to breathe. In doing so, “Mad Men” allows Elisabeth Moss and Jon Hamm to do their best work to date in “The Suitcase.”

This is why “Mad Men” has won three straight Emmys for Best Drama.

Just think — in this episode Peggy finally explodes at Don for taking credit for her work and he explodes back. But unlike Don and Betty or Peggy and her boyfriend Mark, they don’t give up on each other. Within minutes Don is calling Peggy into his office to laugh about Roger’s ramblings on Ida Blankenship, Queen of Perversions.

They are extensions of each other and both extensions are good at moving on. This never happened. It will shock you how much it never happened.

Later, Peggy opens up to Don about her baby (Don doesn’t know it’s Pete’s but we could get to that level of openness) and Don tries to deck Duck (say that 10 times fast) for calling her a “whore.” (Believe me, Don knows from whores and Peggy is no whore.)

Peggy stands over drunk Don like he’s literally watching himself from a far, asking how long he’s going to go on like this. Don cries openly in front of Peggy, treating her like the extension of himself that she has really become.

And yet, toward the end of the episode — after Don gets up from Peggy’s lap and Peggy is woken up from her office — they are still Peggy and Don. Don doesn’t freeze her out like he froze out Allison. Peggy doesn’t rush home to change before approaching Don in her professional woman mode. They touch hands. Not in a romantic way, but in a Don/Anna “I know you and accept you” way.

At the very end, Peggy asks Don a very important question: “Open or closed.” She means the door, but we know it means more than that when he says “open.”

God I love this show.

15 best shows on TV: You should be watching ‘Mad Men,’ ‘True Blood’ and these others

Catch up on my “Mad Men” archive here.