Lily James was made for fairy tales.

The English actress, 34, who gained attention on Downton Abbey and made her first big screen splash in Kenneth Branagh’s Cinderella, channels her charms into a new kind of fairy tale in Finally Dawn during a never-ending night in mid-century Rome.

When Mimosa (Rebecca Antonaci), a young Italian woman, auditions to be an extra in a production at Rome’s Cinecatta studios, she finds herself thrust into a world of American movie stars and mercurial dispositions. Handpicked by legendary movie star Josephine Esperanto (James) to portray an elevated extra role, Mimosa ends up spending a wild night with Jo, dim leading man Sean Lockwood (Joe Keery), and a fairy-godmother of a chauffeur, Rufus Priori (Willem Dafoe).

Written and directed by Saverio Costanzo, the film swaps between English and Italian as it chronicles the dreamlike quality of a night that eventually descends into a nightmare. It’s as if the events of Babylon took place in one night in Italy.

Given the reputation of Cinecitta in the mid-50s, it’s a delight to see it brought to life in this fictional context — and Costanzo has a tongue-in-cheek approach to the magic of the movies. Antonaci is an intriguing new face, her face a cipher for the confusion and excitement she experiences as she’s thrown into a world that is way over her innocent head.

But James is the main attraction here, bringing hauteur and a mid-Atlantic accent to the streets of Rome. Josephine is a fictional blend of fierce, stormy women like Ava Gardner and Elizabeth Taylor, and James masters the enigmatic energy that made them into screen sirens. Sporting a ballgown and a red wig, she transforms into a woman whose false trappings barely conceal the loneliness underneath. Josephine is both a primo diva and a lost child all wrapped into one, and James delivers these complicated layers with gusto. Jo’s selfish need for a plaything is immature in the extreme, and yet, she is riveting and charming all the same. James consistently delivers across contemporary and historical films, but this era might just be her sweet spot. Dafoe is mischievous and caring here in equal measure, a protector to Mimosa, though he ultimately puts his own interests first.

But Costanzo crafts a Rome of the 1950s that feels far too modern. Not in terms of the action or the language of the script, but in the way the film offers audiences a highly polished sheen that feels almost sterile in its approach. We’re meant to see this as a night of absurd excess, yet there’s a sense of contemporary detachment that prevents that from coming through.

Additionally, the actors — excepting James and Dafoe — feel distinctly modern. It’s not that they need to adopt a different tone of voice or seem deliberately old-fashioned in any way; it’s their emotional energy and the way they carry themselves. Costanzo wants to tell a story set in the past, but he doesn’t spend enough time fine-tuning the particulars that make period pieces feel vital rather than stagey.

Additionally, at 140 minutes, the film is self-indulgent in length. We are meant to feel the interminable aspects of Mimosa’s wild night out and empathize with her inability to escape this increasingly unhinged and dangerous world. But the pacing is so clunky that it’s difficult not to check your watch, rather than feel the impact of the narrative technique of its length. The picture could easily lose 20 to 30 minutes and pack a more powerful punch. Finally Dawn is a surreal vision of coming-in-age via cinema, and James fully sells the movie star mayhem at its center. But it can’t overcome its meandering script and hollow depiction of the era.