One of my favorite films of the last decade and a half is Jason Reitman’s hilarious satire “Juno” (2007). This quirky tale of teenager Juno MacGuff’s unexpected pregnancy was the Oscar-winning best original screenplay by Diablo Cody. Its wonderful ensemble cast included Elliot Page, then known as “Ellen,” Michael Cera, Allison Janney and J.K. Simmons.

When Reitman and Cody reunited in 2011 with “Young Adult,” somehow the magic was missing. The story wasn’t nearly as funny or edgy and the cast was lacking, too. But the third collaboration with this writing and directing team in 2018’s overlooked “Tully” was a wonderful comeback.

“Tully” is a truly original dramatic comedy about the emotional troubles of modern motherhood. Charlize Theron plays Marlo Moreau, a struggling New York suburbanite who is about to be a mother for the third time. She has an otherwise normal eight-year-old daughter Sarah, who can be a little hard on herself, and a five-year-old son Jonah, whose kindergarten teachers label him as a troubled student, saying he needs a one-on-one aide.  Her husband Drew (Ron Livingston) is clueless about the demands of being a mom, so her wealthy brother Craig (Mark Duplass) offers to hire a night nanny named Tully (Mackenzie Davis) who helps her cope with her newborn and get her through the first few months with the new baby.

When Marlo’s brother first suggests that his baby present to her will be a night nanny, Marlo’s initial response is, “I don’t want a stranger in my house bonding with my newborn every night. That’s like a Lifetime movie where the nanny tries to kill the family, and the mom survives, and she has to walk with a cane at the end.”

With more typical touches of Diablo Cody’s sarcasm, Craig replies, “We had one. They’re like ninjas; they sneak in and out. You don’t even know they’re there.”

Once baby Mia is born, Marlo’s life becomes maddening. But then almost like Mary Poppins, the night nanny arrives. The 20-something young woman calls herself simply “Tully.” She’s calm, philosophical and constantly reassuring Marlo as Mia settles in. Within days, Marlo is feeling significantly better. The house is cleaned up, cupcakes are made for Jonah’s classmates and the entire family is happier. Marlo wonders how she does it all. Tully’s simple response is: “I’m like Saudi Arabia. I have an energy surplus.”

But not everything is exactly as it appears to be, as Tully seems to exclusively interact only with Marlo and baby Mia. As Marlo becomes more comfortable and appreciative of her new pal and savior, she discusses her personal relationship with Drew and her shared interest in literature, music and favorite drinks, while Tully offers little about herself and her private life.

In one truly inventive sequence, Reitman shows many of Marlo’s busy daytime activities while the song “You Only Live Twice” plays on the soundtrack. This John Barry/Leslie Bricusse song is very effectively reinterpreted and sung like a slow ballad by the musical group Beulahbelle. This song, originally used as the theme to the 1967 James Bond film, adds new thematic poignancy with lyrics like, “You only live twice, one life for yourself, and one for your dreams.”

Cody’s tale takes on a load of surprises when after one evening, Tully suggests that she and Marlo slip out for a night in Manhattan and then reveals she’ll be leaving Marlo. Some bad things happen, new understandings are achieved and all is resolved peacefully.

Theron, who is simply outstanding as Marlo, reportedly gained 50 pounds on a doctor-supervised diet to get into the role of a depressed new mom. Much like Robert DeNiro’s weight gain transformation for his role of Jake La Motta in “Raging Bull,” Theron creates a compelling, brutally honest character.  Her interactions with Mackenzie Davis reveal so many aspects of her desperate character with such compassionate insights. Her character’s highs and lows make for such a refreshing story and make “Tully” one of the more creative serious comedies of recent years.