My wife is pregnant. In turn, Tully is a vision into a nightmarish hellscape of misery. It’s also an extremely good movie, albeit one that takes an unexpected turn that simultaneously works perfectly and feels like a disappointing deception.

Charlize Theron is fantastic in the Jason Reitman-directed, Diablo Cody-written drama-comedy, in which she plays an exhausted, inflated and bloated mother of three named Marlo, including a newborn baby that threatens to push her already limited tolerance for a horrible existence to an entirely new level. Her brother, realizing her pain, hires her a night nanny—Tully (Mackenzie Davis), a young woman who arrives at the house every night to take care of the baby, and Marlo.

Cody, Reitman and Theron last collaborated for 2011’s Young Adult, which coincidentally or not was also Reitman’s last good movie. Tully finds all three at the top of their game, with Theron delivering an award-worthy performance (Mackenzie, too, is great), Cody writing the shit out of the movie like she did back in her Juno days, and Reitman serving up a tight, efficient and highly entertaining film.

Tully is funny (and, again, as a soon-to-be parent, completely frightening) and thrives off Cody’s sharp screenplay. Each scene bursts with energy and life—even when Theron’s character is demonstrating none of either—and is written and acted to perfection.

It’s the third act where things go off the rails—intentionally. The turn Tully takes is completely unexpected and arguably unwanted, though the way Reitman and Cody handle the shift is masterfully done and brings the film’s true purpose to clarity.

However, in the moment it is such a sudden and arguably unwanted change of direction that it doesn’t entirely work. Tully takes on new meaning, and when you’ve spent the last hour laughing, it’s a big pill to swallow.

Still, what Tully transforms into is fascinating in its own regard, and what it depicts is equally so. Few films have explored such subject matter, and for that it should be commended.

Though the ending doesn’t necessarily sit well in the moment, Tully is a movie that stays with you long after it’s over. Funny—until it’s not—and superbly written and acted, Tully is undoubtedly one of the better movies of the year.

Review by Erik Samdahl unless otherwise indicated.