"Tully" will likely work in different ways for different audiences. For purposely child-free viewers, it will confirm they've probably made the right decision to not be parents. For those who want kids, it will provide comfort that all of the challenging times ahead will be offset by the fulfillment which comes with shaping a young mind into the person they'll become. And for those viewers with offspring, it will act as reassuring salve; away from the often rose-tinted image people present on social media, all parents do, in fact, experience days when they feel like they're not good enough and maybe, just maybe, want to step outside their car and scream at the top of their lungs. The third collaboration between director Jason Reitman and screenwriter Diablo Cody (following 2007's "Juno" and 2011's "Young Adult"), "Tully" makes a lingering and compassionate mark by telling it like it is. Only in an abbreviated third act that makes a sharp, not entirely necessary right turn does it arguably take a leap too far. By this point, though, the film has already cast its unique brand of magic.

Marlo (Charlize Theron) is about to give birth to her third child and she's already got her hands plenty full with a kindergarten-aged son, Jonah (Asher Miles Fallica), whose emotional needs have drawn concerns from his school's principal (Gameela Wright). When newborn daughter Mia arrives, her already fatigued, high-stress reality only becomes more wearying and repetitious, each practically sleepless day blending into the next. Husband Drew (Ron Livingston) helps with homework and packing lunches, but his job keeps him away until evening. Marlo realizes something has to give if she hopes to live up to the mother she wants to be.

On the suggestion of her brother, Craig (Mark Duplass), she decides to hire a night nanny—someone who sweeps in to care for the baby while bringing a newfound stability to the family's life even as the lot of them sleep upstairs. Arriving at Marlo's doorstep is 26-year-old Tully (Mackenzie Davis), an enigmatic young woman with a vivacious intelligence and a gift for nurturing those around her. She is exactly what Marlo has been yearning for and didn't know she needed, the helping hand giving her the energy to finally look within at the life she's made for herself—a life, it should be said, not at all like the one she imagined when she was Tully's age.

"Tully" is a refreshingly honest snapshot of motherhood, a domestic slice-of-life with sneaking wit and raw empathy. Its candid observances aren't always pretty, and yet there's something rather special and poignant about its ability to key into the minutiae of everyday life. Charlize Theron (2015's "Mad Max: Fury Road") is a miraculous Marlo, painting a moving, nuanced, three-dimensional portrait of a woman who feels as if her identity, whether she likes it or not, belongs solely to her children.

Marlo's evolving relationship with Tully provides a number of surprises which shouldn't be spoiled here. What deserves to be mentioned is the wonderful work of Mackenzie Davis (2017's "Blade Runner 2049"); for the bulk of the narrative, little is learned about her crucial title role and yet Davis ensures she remains complex, full-bodied, and thoroughly appealing. Ron Livingston's (2013's "The Conjuring") part as Drew could have easily been thankless, but Diablo Cody takes the time to make sure he and his marriage to Marlo have a vital place within this story. Small in size but not impact are a number of sharply written and performed supporting roles from Mark Duplass (2015's "The Lazarus Effect") and Elaine Tan (2014's "Inherent Vice") as Marlo's seemingly put-together brother and sister-in-law Craig and Elyse; Gameela Wright (2014's "They Came Together") as Jonah's sympathetic principal Laurie; and Tattiawna Jones (2014's "RoboCop") as Violet, a stirring reminder of Marlo's past life.

"Tully" affectingly melds naturalistic humor and unforced emotion into an unsuspectingly evocative whole, while dream imagery of mermaids and nightmares of encroaching danger sprinkle it with the dust of a classic fairy tale. This almost subconscious fable-like aura goes a long way toward accepting the places the story goes near the conclusion. The final scenes hold a bittersweet but somewhat uneasy touch, serious subject matter used almost as fodder for a twist ending that doesn't have the time to treat it with the same authentic sensitivity as what has come before this point. The tender, humane layers left in its wake, however, are countless. A film about the extraordinary nature of ordinary lives, "Tully" is unfiltered and messy and altogether kind of beautiful.