But everyone functions as if not uttering words like postpartum depression or autism spectrum will keep their fears from being realized. Marlo sinks further into isolation after the birth of Mia, her maternity leave succinctly rendered onscreen as a groaning cycle of fatigue with contrapuntal onesie snaps. The arrival of night nurse Tully (Mackenzie Davis), a ghostly figure tapping on the textured glass of their modest middle-class house, signals a shift in Marlo's perception. She doesn't know what to make of this boho caregiver in high-waisted jeans and crop top, bubbling with enthusiasm and ready to dive into Marlo's life. Tully soon becomes a confidante and sounding board, the kind of supportive female friend this overextended working mom didn't realize she'd been missing.
Cody often employs a third act surprise, but with Tully she reveals a downright Shyamalanian capacity for alienating an audience with a major plot twist. She takes the calculated risk that viewers will treat the story of a woman re-evaluating her life with the same seriousness as a mathematician tackling an unsolvable equation -- and it works.