"The Other Woman" is not only season five's best episode -- by a wide margin -- it ranks alongside "The Suitcase" as one of the the best "Mad Men" episodes ever; proving once again that Matthew Weiner and Co. are at their best when they slip into the clutches of the peculiar gender warfare that is always brewing below the surface of Sterling Cooper Draper Pryce's day-to-day operations.

The titular woman is not made of flesh but of steel: SCDP wins the coveted Jaguar account by anthropomorphizing the car as a mistress who -- unlike the kind who can walk and talk -- can be controlled by a man of means.

"At last, something beautiful you can truly own," boasts the winning campaign tag line -- compliments of Michael Ginsberg. But it is Joan who seals the victory by agreeing to spend an evening with a smarmy Jaguar exec who makes it clear that getting to know her would make or break the deal.

Naturally, Pete Campbell brokers the tryst -- with the help of Lane Pryce, who has his own desperate motivations. Of course, both approach Joan with an underhanded pitch, of the 'forgive-me-for-suggesting-you-would-ever-consider-this...but' variety.

If Joan is shocked by the indecent proposal, she conceals it well, telling Pete that it's out of the question, but suggestively adding that the company can't afford it. Of course, SDCP truly cannot afford the $50,000 finders fee Pete promptly suggests to the partners, but only Lane -- who has secretly extended the company's line of credit and embezzled $8,000 of it for himself -- knows that. Proving once again how dirty he can play when his back is up against a wall -- and is it ever -- Lane baits Joan with the $50k sum. Once he has her attention, he convinces her that a stake in the company is in her better interest than a one-time payout. Though Joan chides Lane for conspiring to prostitute her, she's angriest at Roger Sterling for failing to stand up and defend her honor. A Chavalier Blanc he is not.

According to our calculations, $50k in 1967 would get you as far as nearly $350,000 would today -- which, if managed with care, could very well improve a single mother's circumstances for the long term. In the end, Joan demands a five percent stake and a non-silent partnership -- ostensibly the more practical choice and one that will allow her to rub Roger Sterling's face in it for ever more.

But $19,000 is quite a bit for a young and childless climber like Peggy Olsen -- it's $1k more than the asking price she brings to a meeting with Don's arch rival after suffering yet another in long series of indignities. This time, Peggy saves the Chavelier Blanc account with a heroic, off-the-cuff campaign rewrite that leaves her co-workers' jaws on the floor. But not only does Don withhold his applause, he reminds her that it's Ginsberg's account and that she isn't entitled to the fruits of her labor. When she protests, he throws some money in her face. Literally.

Still, if not for Don, Peggy might still be a secretary. Though she has no choice but to accept the competitor's offer -- which comes with the title of Copy Chief -- she dreads breaking the news to her mentor. He makes it easier by behaving like a d*ck: First, he tells her that he can't put a girl on the Jaguar account; then, after Peggy tells him what she is really there to say, he takes credit for everything good that ever happened in her life. But Don gives his heartbreak and his respect away when Peggy extends her hand: instead of shaking it, he kisses it, like a supplicant would his queen.

All of Don's women let him down in this episode: Megan is up for a role that would take her to Boston for three months, and in general, is doing a worse and worse job of pretending to believe that Don's life and career are more important than her own. But it's Joan who -- unwittingly -- commits the ultimate betrayal, as she was led to believe that all of the partners had voted in favor of her becoming a Woman of the Night. Only after it's too late does Don find out that he did not effectively close the subject when he rejected the idea: Pete reminds him that "the conversation doesn't end just because you've left the room."

When Don rushes to Joan's apartment to talk her out of prostituting herself, he doesn't know that she already has. And she doesn't know that Don was against the idea all along. If she did, she probably wouldn't have gone along with it either. All she needed was one person whose opinion she cared about to show that he cared about her.

The episode's title could also allude to the reality that here in 1967, women fall into one of two categories: You're either a Peggy, or you're a Joan. And if you try to be both -- as Megan seems to be -- you run the risk of failing to be either. Megan wants to be a success in her own right, and she's willing to fight for it, but she's not willing to give up her role as trophy wife. As Megan's friend reminded her (and us) a few episodes back, Megan wouldn't have the leisure to pursue an acting career if it weren't for Don and his gilded cage.

Peggy may still be too young and too driven to know or care what she might have lost by becoming one of the boys. But what if, five or 10 years down the road, she changes her mind? What if her mother was right, and she's not the woman Abe will ultimately marry and have children with? Will everything she's worked for be enough when the path she chose not to take isn't a choice anymore?

By performing the ultimate act of female subservience, Joan (technically) has more power at Sterling Cooper Draper Pryce than Peggy ever did, and likely ever would have. And there is probably no other way she would have gotten there. But in the process, she -- perhaps unfairly -- lost the respect of the man she holds in the highest esteem. Without the promised payoff -- which may never come if Lane continues to drain the company coffers -- Joan could end up in a worse position than where she started.

For all of her clipped confidence and capability, we have to remember that Joan is a woman who married her rapist, and had a child by a man who maybe loves her but is usually married to someone else. As long as she believes that others see her sexuality before they see anything else -- and how could they not? -- she will probably always, in one way or another, be as much a victim to her own seductive charms as the men who drool in her wake. For Joan to believe that she could live successfully in a man's world without playing into male fantasies would be like trying to hide her most visible assets under a thicker cardigan or a looser dress. It will never work, so why bother?