In Tully, Jason Reitman’s third collaboration with screenwriter Diablo Cody after Juno (2007) and Young Adult (2011), the pregnant Marlo (Charlize Theron) responds to all mentions of her soon-to-be-born child with a forced, dead-eyed smile, as if on autopilot. When someone congratulates her, it takes her a couple moments to realize what they’re talking about. “Such a blessing,” she mutters, staring into space. Not only are these moments in the film hilarious, thanks to Theron’s razor-funny deadpan, but they also feel radical in their irreverence towards the clichés we glibly recite about motherhood, often papering over its emotional and physical toll. What if it’s not always an uplifting miracle? What if it sometimes comes with loneliness, exhaustion and severe postpartum depression? When Marlo finally has her daughter, her face looks drained — no tears of joy, none of that new-mommy glow that usually lights up birth scenes in movies.

In many ways, Tully is a spiritual successor to Young Adult: if ex-prom-queen Mavis (also played by Theron) was stuck in perpetual and self-destructive adolescence, Marlo is mired in middle-aged motherhood, having all but forgotten what it was like to be her young and blithe self. Mavis would probably sneer at Marlo’s suburban life: she has an HR job she doesn’t especially like, a husband who’s nice but oblivious and ineffectual, an eight-year-old daughter Marlo has hardly any time for, and a special needs son Jonah (whom everyone politely refers to as “quirky,” much to Marlo’s chagrin) on the verge of being kicked out of his private school. Her wealthy brother Craig (Mark Duplass) fears that the unplanned third child will cause Marlo to relapse into the breakdown she experienced after the birth of Jonah, and he offers her a gift: a “night nanny” to watch her baby while she sleeps. Marlo refuses, scoffing at the ridiculous bougie-ness of the idea.

Reitman and Cody have a way of making psychosomatic malaise feel discomfortingly visceral — if there’s one image from Young Adult that’s burned into my mind, it’s Mavis compulsively pulling at her hair. In Tully, it’s everything: Marlo’s haggard, defeated face as she wakes up in the middle of the night to feed the baby, her swollen feet that frequently step on stray Legos, her fatigued post-pregnancy body that she describes, in one of the film’s excellent black comedic lines, as resembling the “relief map of a war-torn country.” By the time the pressure-cooker moment arrives — with Marlo and Jonah screaming at each other inside a tiny car, as Reitman ratchets up the sound to an unbearable crescendo — the viewer will desperately want her to call that nanny. She does, and in waltzes the bright-eyed, wide-smiled Tully (Mackenzie Davis), radiating joy and promising to fix all of Marlo’s problems.

There’s a calculated precision to both Reitman’s direction and Cody’s screenplay. The film is perfectly paced and cut, and moves with a rat-a-tat rhythm; the writing is sharp and specific, with a zinger in every other line. These energies synthesise to produce some masterful montages. One depicts Marlo’s babycare routine in rapid repetition, full of hilarious little details such as Marlo struggling with the diaper genie, accidentally dropping her phone on the baby’s face or pumping breast milk while watching the Showtime series “Gigolos.” In another, a drive to New York is compressed into a staccato series of shots that cycle, in snippets, through the entirety of Cyndi Lauper’s She’s So Unusual album.

And yet, despite the meticulousness of Reitman and Cody’s craft, a loose and warm energy courses through Tully, exuding in particular from the chemistry between its leads. Theron’s performance as Marlo is magnificent — worn-out, yet witty; tired, yet tender — and it mellows beautifully in response to Davis’ ball-of-sunshine breeziness. Marlo starts to feed off of Tully’s youth, staying up late to drink sangria with her in a never-used hot tub, allowing the girl to do her makeup, and taking her advice about spicing up her dull sex life.

It’s all very moving and affirming to watch, but there’s something about Tully’s New Age aphorisms and self-care mantras that rings a bit false — as does the idea that hiring some help is the magical solution to postpartum depression. However, the film shows itself to be well aware of these skepticisms. It exploits them cleverly in a final reveal that, although a bit contrived, deepens and darkens the film as a commentary on mental illness and the almost-invisible gender imbalances that can make parenting especially hard for women.

Devika Girish (@devikagirgayi) is as a freelance film critic. She writes for Film Comment, Village Voice, Reverse Shot and MUBI’s Notebook, among others. She grew up in India, studied film and critical theory at Brown University and will soon start a Master’s in Specialized Journalism at the University of Southern California.