If Diablo Cody and Jason Reitman don’t have a pact to work together every four to seven years, they should seriously consider making one.

The team behind Juno and Young Adult hasn’t fared well without each other, namely the writer’s borderline pointless Ricki and the Flash and the director’s lifeless Labor Day and absurd Men, Women & Children, but in reuniting for Tully, they rediscover the collaborative magic that’s made their prior pairings so great.

Looping in their Young Adult star Charlize Theron as overextended mom of two (and about to be three) Marlo, the duo offer an intelligent, witty and wise look at motherhood and the help that’s often required to achieve sanity with children.

Packed with honest details, Tully sports nearly as many images, actions and lines that incite laughs as those that are felt yet stifled out of respect for the many matriarchs in one’s life.

Though the film successfully hovers in the dark humor territory of its core trio’s prior film, the mood takes a gradual sunny turn when the baby is born and the titular night nanny (Mackenzie Davis, Blade Runner 2049) hired as a gift by Marlo’s wealthy brother Craig (Mark Duplass) starts lightening Marlo’s load and giving her time to sleep.

The positive impact of Tully’s aid on Marlo, her husband Drew (Ron Livingston) and their other two children is a joy to behold, though it’s a dynamic all know is temporary and one whose inevitable undoing carries gut-punch consequences.

In arguably her best screenplay to date, Cody tackles big, mature themes in entertaining fashion, and by returning to comedy, Reitman rediscovers his flair for filmmaking, pulling strong performances from his central cast and crafting delightfully creative stretches such as measuring the length of a car ride with chronological snippets from Cyndi Lauper’s She’s So Unusual.

It’s such a welcome victory that it’s tempting to want the pair to exclusively band together for each new project, but seeing how elevated the quality of their art has been after multiple years apart, perhaps it’s best to stick with this winning formula.

Grade: A-minus. Rated R. Now playing at the Fine Arts Theatre