Tully

"Rosebud." "Luke, I am your father." "Soylent Green is people." One pivotal line can make all the difference to the meaning of a film, and Tully has such a moment. Days after watching it, I'm still not sure whether it knows what to do with it.

A decade after director Jason Reitman and writer Diablo Cody collided with the whip-smart repartee of Juno, and their second collaboration (after Young Adult) with Charlize Theron, Tully is arguably both filmmakers' most mature work – as in, forced to grow up. Marlo (Theron) is two kids deep into an OK marriage to Drew (Livingston, still the king of the soft-spoken everyman). The third offspring, now that's the one that's kicking her ass, especially since her daughter Sarah (Frankland) is already shrinking into the background while her son Jonah (Fallica) is ... well, everyone calls him quirky, but that's neither a description nor a diagnosis for his bouts of rage. Three kids, phew. Between dealing with principals, organizing kids' parties, and chafed nipples, Marlo can't even pretend she's a kid herself anymore. Especially when Sarah deadpans one of the most perfectly horrifying questions about an adult imaginable.

That's when Mary Poppins flies into her life. Or, rather, Tully (Davis), a night nanny recommended by Marlo's annoyingly perfect brother Craig (Duplass). A seeming miracle worker who can survive on a diet of yogurt and leftovers, who can calm every crying infant, and sneaks in and out of the house at night without leaving even a crumb or misplaced hair. She's also the only one that realizes it's not the baby that needs looking after – it's Marlo.

There is an undeniable spark in the Reitman/Cody mix. Her almost-naturalistic dialogue – best spoken by actors who understand her arch intent, and the performative edge with which she imbues her characters – illuminates his laconic filmmaking, while he lets the wit breathe without overly-stylized embellishments. Moreover, Theron, as always, fearlessly embraces every inch of Marlo – her love, her stretched-nerve desperation. Underneath her interactions with the charming, nurturing, wise-beyond-her-years Tully, there is the desperation of her own lost youth and sense of self.

But the hook in the eye is that one line. It's the moment when Tully should face-slap straight into sharp focus, and yet it's weirdly understated. Blaming the delivery or the direction or script seems off, but something about this key moment is awry. When days after, rather than thinking about one of the rawest depictions of motherhood and especially of postpartum depression, it's that line that still stands out, it's a flaw that undercuts some, though far from all, of the work done before. Reitman sets up that not all that meets the eye with Tully is as it seems – little hints in her outfits and her turns of phrase – so the knowledge that the other shoe will inevitably drop is baked into the equation; but that one tiny moment, rather than informing how the third act plays out, is almost swallowed whole. Yet that tiny slip cannot undercut a charming, touching, and deeply compassionate depiction of modern middle-class motherhood.