And the secret is...
...well, before we get to that, we have to talk about that all night party. Don leaves for home and that's when the big party begins. The gang gets out all the booze and cigarettes and drags the TV into the middle of the office to watch election results. There's even a water cooler filled with Creme de Menthe (and later, a trash barrel filled with Creme de Menthe vomit, but let's not talk about that image).
The girls are tipsy and the guys are all unbelievably un-P.C.: Paul chases Helen, tackles her, and actually puts his hand up her dress to see the color of her panties (the guys had a bet - ah, the days before sexual harassment lawsuits), Harry and Hildy get it on in his office (he breaks his glasses), Peggy is all business-like and unhappy at the way everyone is acting, and Paul and Joan dance and talk about their former dalliance (Joan didn't go any further back then because he has a big mouth). Speaking of mouths, Joan locks hers with Sal. No, it was just part of the play that Paul is writing. When they kiss, the look on Joan's face is either "wow, he's a better kisser than I thought!" or "hmmmm, I think he might like guys."
I thought Pete might have a change of mind about blackmailing Don after a talk with his wife, but he's even more blunt about it than I thought he would be. But it backfires, of course (Pete is evil but incompetent about it). Cooper doesn't care about it even if it is true. Pete is confused.
And what is the "it" I speak of? Pete doesn't even know these details, but one of Don's commanders in Korea was accidentally blown up after Don dropped his lighter. This was the real Don Draper. Dick Whitman immediately changed dog tags and the army assumed Don was Dick and Dick was Don. So Don isn't an evil guy - it's not like he murdered someone in his past - though the morals of it are shaky.
One of the reasons - the many, many reasons - I like this show is because I truly have no idea where it's going. It has plunked me down in the center of 1960 New York City and I've been engulfed in an unpredictable drama that completely has my attention. The season finale is next week and I have no idea how the events of this episode are going to play out in the season finale and set up next season.
And if Jon Hamm isn't nominated for an Emmy...