“TULLY”

****

(R, 1:36)

Screenwriter Diablo Cody won an Oscar for her debut screenplay for “Juno,” directed by Jason Reitman, and firmly established her unique voice — sarcastic, smart and referential, a singular blend of self-deprecation and superiority. With Reitman, Cody has explored the outer ranges and growth of this voice across the various stages of life, from the young, snarky pregnant teen Juno, to the single, embittered novelist returning to her hometown in “Young Adult,” and now to an exhausted, middle-aged mother in “Tully.”

Charlize Theron, who delivered the barbs of “Young Adult” with such flair, completes the artistic trifecta with Reitman and Cody once again in “Tully,” playing Marlo, a heavily pregnant mother of two just trying to get through the day intact. Already frazzled, things are looking bleak with the arrival of her third child. Jonah, her kindergarten-aged son, is troubled; her husband, Drew (Ron Livingston), is passive. Her wealthy brother, Craig (Mark Duplass), is ostentatious and obnoxious.

Marlo gets through the day with a forward-­facing smile that turns into a derisive sneer behind closed doors, but that careful balance is about to be thrown entirely off.

Craig presents Marlo a baby gift: the services of a night nanny. At first, Marlo rebuffs the offer. Soon, however, her cycle of feeding, pumping, diapering and homemaking (frozen pizza and microwaved broccoli) comes to feel brutally punishing. And after a particularly rough day dealing with school administration, who’d like the family to hire an aide for Jonah, she cracks and digs up the number.

Tully (Mackenzie Davis), the nanny, arrives on her doorstep at night, a bright-eyed font of girlish awe and wonder, spouting fun facts and positive vibes, sporting a taut, 20-something body, taking the baby off her hands, letting Marlo sleep, cleaning the house and baking cupcakes. “I’m here to take care of you,” she says. “You can’t fix the parts without treating the whole.”

Through Tully, the drowning Marlo works her way to the surface to catch a gasp of air. She’s a drowning woman, and it appears Tully could be the mermaid who rescues her from the crushing pressure she’s under.

THE FILM explores the taboo of modern culture around the idea of seeking help with family difficulties, in particular “hired help,” with the uncomfortable discussions over Jonah’s classroom aide, and the revelation of Marlo’s favorite TV show, “Gigolos.”

Is there anything wrong with getting assistance, and paying for it, or does it reveal a crack in the illusion of perfection?

Theron embodies Cody’s voice with ease and aplomb, making clever quips sound organic to her specifically caustic personality. In “Tully” there’s a true sense of flow among the collaborators, despite the dark material. And Cody’s writing is restrained and efficient — it says a lot with a little, suggests but never overexplains.

Reitman creates a realistically drab enough world to reflect Marlo’s dark reality, with a cluttered, out-of-date house, editing together montages of endless feedings and terrifying dream sequences and hallucinations. The film looks exactly like the inside of Marlo’s mind, just as her exterior appearance reflects her internal struggle.

“Tully” slowly reveals itself to the audience as a far more psychologically complex tale than simply “woman hires a nanny.”

Marlo is struggling with her identity as a mother, with the idea of normalcy as a gift to her children bumping up against the struggling mundanity of her suburban life. It’s an emotionally deep yet concise rumination on the nature of modern motherhood.

“Tully” shatters the notion that mothers can do it all, have it all and make it look good, presenting motherhood in all its gross and glorious struggle, and asserts the idea that we all need a little help sometimes, in whatever form that takes.