Why can't women stay friends?

That's a trick question, of course, but also one that British actresses Emily Mortimer and Dolly Wells -- lifelong pals in real life -- attempt to answer earnestly and honestly in their new HBO cringe comedy Doll & Em. In the six-episode series, Mortimer and Wells play sitcom versions of themselves as a thriving Hollywood thespian and her best-friend-turned-personal assistant, respectively. One has reached just about the highest level of success a middle-aged film actress not named Meryl Streep or Cate Blanchett can; the other is so lost any opportunity looks like a step up. They reside in the same rented house, but live in entirely different worlds.

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As the series' creators and writers (the latter with Azazel Jacobs, who directs every episode), Mortimer and Wells blame the mildly acidic but frighteningly fast corrosion of their characters' decades-long friendship on a familiar culprit: female competition. Dolly and Emily's passive-aggressive conflicts -- about men, career opportunities, and money -- are framed as an acknowledgment of a bitter truth: Close friends often make rivals of each other. Where this moderately ambitious show best succeeds is in justifying the competition between the two friends in the show's particular context. Their rivalry is dirty and ugly, but also makes emotional sense.

Set largely on a film set in Los Angeles, where attention, kindness, and dignity are scarce, Doll & Em frequently resembles a struggle between two fundamentally affable dogs over a bone. Whether that bone's just made of hard-packed dirt or something truly meaty is anybody's guess. Dolly and Emily are self-aware enough to know they shouldn't be bitches to one another, but they're both afraid that that bone might be the last one they ever lay eyes on.

By necessity, Doll & Em takes the outsider-looking-in perspective of Dolly, who moves from London to Los Angeles after a bad break-up, hoping to find solace in her best friend's arms. For the few months that Emily is filming a movie away from her family in New York, Dolly agrees to help her out. "What does an assistant do? Do I make you breakfast?" she asks on her first night. "Do I wash your clothes?" Both are too sleepy from their bonding wine to figure out the basics.

Dolly, then, is set up to fail. She's also not the hyper-competent type -- she has trouble adjusting to the left-side driver's seat and accidentally gives the small boy she's babysitting (Susan Sarandon's toddler son, in a joke that doesn't quite work about the sixtysomething actress's eternal youthfulness) a minor injury at a cast-and-crew party. When Dolly's impatience gets the better of her, she takes it out on her friend -- she's no picnic or pushover. Emily is sweet but obliviously spoiled and quietly needy in her own way, especially when other women in the industry knowingly wag their brows at her age.

The friends' mutual insecurities build to a hilariously awful bout of one-upmanship in the second episode, when they compete for the affections of a skeezy player in his hot tub. They recount how they met as kids -- their dads were friends -- and then transform their compellingly heartbreaking relationships with their deceased fathers into a game for sympathy-sex points. "My dad died last year," volunteers the married Emily. Dolly, not to be outdone, says of her own father, "I didn't realize he was my dad until I was about 11. I thought it was someone else entirely." The tragic details pile up to an absurd denouement in which Emily declaims a poem in Russian in memoriam of her father. When the guy is suitably impressed, Dolly storms out of the hot tub. Whether she's jealous of her friend's education, worldliness, or artsiness, it's clear that the roots of their currently rivalry were sown long ago. No crop grows faster in Southern California than envy.

From the third episode on, Doll & Em digs its heels into showbiz satire by taking on an All About Eve-esque storyline. Dolly impresses the director and other cast members with her free-flowing tears when Emily can't produce them on cue. Dolly tells Emily she just thinks of her dead father, natch. (The real-life Wells has three dozen screen credits to her name, but her fictional counterpart isn't at all interested in acting until she's "discovered" on set.) It's not long before Emily is threatened by her friend's new aspirations, though her substantial anger and feelings of betrayal are tempered by her loyalties.

Doll & Em arrives amid an epidemic of sororal dissolutions onscreen. Over on Girls, Lena Dunham is distinguishing her more naked, less erotic show from older sister Sex and the City by incrementally -- and painfully -- separating its central quartet. But Dolly & Em is more comparable to last year's Blue Jasmine and Enough Said, two films that exploit post-recession blues to explore how adult women compare themselves to their sisters or female friends and find either themselves or others lacking. (Why this theme comes up so much more regularly in stories about women than men remains a mystery.)

All three works share a common yardstick: money. In Blue Jasmine, Cate Blanchett's Ruth Madoff–like protagonist expresses her class anxiety by mercilessly haranguing her working-class sister (Sally Hawkins) to date better, i.e., richer, men. Nicole Holofcener tackles the same premise from a different perspective and genre in Enough Said. Julia Louis-Dreyfus's masseuse character begins to question her perfectly pleasant relationship with her new schlub boyfriend (James Gandolfini) when she discovers that he's the cast-off spouse of a wealthy, chic client (Catherine Keener).

Dolly and Emily compete professionally and sexually, but of course there's no competition, really. That tragic undercurrent gives the series its slightly sorrowful air. Emily may have a lot to lose, but that already means that she has a lot. She never has to give money a second thought, while in the fourth episode Dolly has to ask her friend for enough cash to buy the coffee it's her job to fetch. "I keep forgetting to pay you," Em confesses. She gives the classic Mortimer sad eyes -- her sincerity is never in doubt -- but it's hard not to be enraged by her apology when it's the kind of declaration only a person truly unaware of her privilege is in the position to make.

Doll & Em is an oblique take on that old truism that every successful star pays their friends to hang out with them. But it's also an incisive look at how differences in money and power will inevitably poison the closest of relationships, especially in a pyramidal society like Hollywood's, where a servant class carries top talent on an organic cotton pillow. Hollywood isn't the real world, but the distance between the two gets smaller every day.

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