Millennial Mary Poppins drama with cheap twist

Tully

15 cert, 96 min

Dir Jason Reitman Starring Charlize Theron, Mackenzie Davis, Ron Livingston, Mark Duplass, Elaine Tan

It was a bounce of burnished hair that marked Rita Hayworth’s big entrance in Gilda, while Cyd Charisse stole into Singin’ in the Rain toes first. In the new film from Jason Reitman, the camera tracks Charlize Theron’s nine-months-pregnant belly as it makes its way across her son’s bedroom, only later pulling back to reveal the woman attached.

After the best part of a decade raising two children, Theron’s Marlo has become defined by motherhood. While this hasn’t happened against her wishes, the grinding reality isn’t exactly in lockstep with them either, and the impending arrival of unplanned child number three has her nerves wound triply tight. What she needs is a younger, more energetic double who can shoulder some of her responsibilities.

Tully (Mackenzie Davis) is the 26-year-old night nanny who appears on Marlo’s doorstep – entirely paid for by Marlo’s rich brother Craig (Mark Duplass). The film is self-aware enough to recognise the intensely middle-class-problems nature of its premise – but Theron makes the fine detail of Marlo’s struggle so frazzlingly plausible that only a ghoul would begrudge her help.

And what help. Tully turns out to be something of a millennial Mary Poppins: whip-thin, wide-eyed, unnervingly earnest, and capable of soothing squalling infants with preternatural ease. The Fatal Attraction-esque overtones of a lithe young woman insinuating herself into a married couple’s life are toyed with so slyly that it’s hard to tell what kind of film you’re watching.

Tully is Reitman’s third collaboration with the screenwriter Diablo Cody since 2007’s Juno, and their second, after 2011’s superb Young Adult, to star Theron. There is real, nerve-jangling, fun to be had in watching the various boundary-infringing ways in which Tully’s presence restores sanity, and then even joy, to Marlo’s life. Yet, in order to be “clever” the film sweeps away all of its hard-earned smartness, and the previously gripping uncertainty around the exact nature of Marlo and Tully’s connection is tidied up in a way that feels jarringly cheap. When it pins down the exact point it wants to make, it immediately feels like a smaller, less insightful picture.