“Is this the ballroom? There’s no staircase.”

Don Draper (Jon Hamm), banner of boots and make-up, with his princess of a daughter, Sally Draper (Kiernan Shipka). (Ron Jaffe/AMC)

Oh, Sally Draper. At age 12, she still believes in the notion of fairy tales and the magic of dress-up and the promises that debonair men make. At least she did during this week’s episode of “Mad Men” before accompanying daddy Don to that American Cancer Society dinner and learning a few hard truths. Specifically: that fathers often don’t let their daughters wear go-go boots ; that silver-foxy older man will, inevitably, wind up leaving your side to get oral sex from your stepgrandmother (man, Sally’s discovery of that was dis-turbing); and that the main entree at an awards banquet is often fishier than one might hope.

In the latest installment of “Mad Men,” dubbed “At the Codfish Ball,” there were no glass slippers, only glass ceilings unsmashed. (Note: this marks the second major allusion this season to a fractured Cinderella story.)

That running theme of disappointment was captured perfectly in the poignant yet unintentionally bleak ad campaign for Heinz that Megan — Megan, not Don — pitched.

“Heinz beans: some things never change.”

Or, in blunter terms: “Heinz beans: because you’ll always be eating cheap food out of a can and getting slight indigestion, from now until the end of time.”

Which brings me to Peggy Olson.

Our favorite workaholic with a flip ‘do was convinced that her boyfriend Abe was on the verge of breaking up with her until Joan got hold of her and suggested that, perhaps, he wanted to have dinner with her so he could propose.

“Men don’t take the time to end things,” she advised. “They ignore you until you insist on a declaration of hate.” (Joan Harris, original author of “He’s Just Not That Into You,” ladies and gentlemen.)

Joan was half-right. Abe didn’t dump Peggy, but he didn’t plan to offer her an engagement ring either; he just wanted to suggest that they move in together, still an unconventional suggestion in 1966.

Peggy’s expression said everything about her reaction to Abe’s idea that she, as a determined-to-be-modern woman, could not articulate out loud. It was as if her expectations of becoming a fiance slid off her face and got stuck in the process, leaving behind a half-smile and eyes that could still see the dimming sparkle of withdrawn diamond rings. Well done, Elisabeth Moss.

Joan reassured Peggy that her decision to cohabitate rather than walk down an aisle was “brave.” But Peggy’s mother, otherwise known as The Woman Who Refuses to Serve Cake to Sinners, had a different take.

“You are selling yourself short,” she told her daughter. “This boy — he will use you for practice until he decides to get married and have a family. And he will, believe me.”

Is Peggy’s mom right? I don’t think Abe is consciously using Peggy, but his eagerness to shack up after seeing how Peggy relates to the guys at Sterling Cooper Draper Pryce suggests a determination to assert a more clearly established position in her life. That position, however, does not involve marriage and it’s obvious that Peggy — for all her ambition and focus — still wants that, even though her traditionalist streak makes her feel like a feminist sellout.

Speaking of selling out, let’s switch over to Megan Draper.

(Ron Jaffe/AMC)

Like Peggy’s mother, Megan’s dad — who came to town with Megan’s mother (lovely to see you, Julia Ormond) so they could argue loudly in French — also expressed concern that his daughter is selling herself short by being Mrs. Don Draper.

“You skipped the struggle,” he said of her high-end lifestyle, “and went right to the end.”

Megan also skipped the opportunity to take credit for pretty much every aspect of making the Heinz deal happen. Let’s recap what Little Miss “Zou Bisou” did on this front: She came up with the idea for the campaign, solidified the details for its execution, found out Heinz planned to drop Sterling Cooper Draper Pryce because of her solid relationship with Mrs Geiger, then knew exactly how to make a last-ditch effort to retain the client.

And yet she lobbed all the credit over to Don, which was a savvy move — as established when Peggy was on the account, Raymond was far more likely to respond to Don than to a woman — and a satisfying opportunity for us to watch Megan and Don play a brilliant game of ad pitch volley. This is why they got married; when they’re not arguing over orange sherbert at a HoJo’s, they can be pretty great together.

But Megan also made a sacrifice here, ceding what should have been her territory to her significant other.

Don can’t be blamed for it. He insisted that his wife let her Sterling Cooper Draper Pryce colleagues know it was her idea and championed her efforts to lead the campaign. It was Megan who made the call at that dinner to lead Don down a path toward canned bean victory. Still, she could clearly sense that, even with her husband’s support, this is how it would always be: woman runs marathon, then lets man cross finish line to the sound of cheers.

“This is as good as this job gets,” a supportive Peggy told Megan.

And that’s precisely what Megan is afraid of.

“Heinz beans: some things never change.”

“At the Codfish Ball,” there was no such thing as Prince Charming, not for Peggy, not for Megan, not even for Sally Draper, who is already growing cynical at the ripe age of 12, laying the groundwork for her to give birth in her late 30s to a daughter that will eventually move to New York and catch an STD on HBO’s “Girls.”

The closest thing to a man in Sally’s life, minus her father, is Glen, the more mature yet still creepy kid who takes her phone calls while wearing a winter coat and no pants.

“How’s the city?” he asked at the end of the episode as Sally stood in the shadows of her father’s living room, making a clandestine late-night connection.

“Dirty,” she concluded.

You got that right, Cinderelly.