Buried somewhere underneath the wreckage, there’s a smart little sci-fi film pulsing at the centre of Captive State, a scrappy, unwieldy curio with plenty on its mind, coherence not necessarily included. Shot over two years ago and pushed around the release schedule, it’s a troubled project that feels troubled, with confused editing and clear structural issues clueing us in on its difficult journey to the screen. It’s a frustrating experience but one that remains worthwhile because there’s just enough of a glimmer of the film it could have been to make it worth watching the film it turned into instead.

Us review – Jordan Peele's brash and brilliant beach holiday horror Read more

We’re presented with a familiar set-up: aliens have invaded Earth leading to destruction, division and plenty of dust. But unlike the majority of similar films that have come before, we’re then presented with an idea of what comes after. What if aliens stuck around? What if an uneasy arrangement was made with Earth’s governing bodies? And what if the invaders were now seen as the main legislative force whose presence had actually led to a statistically safer society? It’s a fascinating conceit and one that raises a string of intriguing questions, some of which the film answers with skill.

Pitched somewhere between District 9 and The Purge, writer-director Rupert Wyatt, whose 2011 prequel Rise of the Planet of the Apes was a surprisingly urgent and necessary blockbuster, focuses the action on Chicago and how the new world order affects a city already struggling with crime and economic disparity. His lead is Gabriel, played by Moonlight’s Ashton Sanders, existing in one of the poorer districts and working in a factory tasked with wiping data from digital devices, which have been outlawed. His brother Rafe (Jonathan Majors, a rising star after his charming turn in Sundance darling The Last Black Man in San Francisco) was leading a resistance against the state but after his death, Gabriel finds himself scrambling for an escape.

He’s unavoidably linked to Mulligan (John Goodman), a local cop who worked with his father, now deceased, and who remains convinced that another underground revolution is on the rise. He’s both protective and wary of Gabriel, erring more on the latter as he grows increasingly suspicious of his movements.

There’s something undeniably impressive about a film aiming to do more than its budget would traditionally allow and while not quite as audacious as 2010’s similarly themed Monsters (which attempted to tell a story of alien invasion with just $500,000 at play), Captive State is still admirably plucky. Marketed as a major multiplex action movie, it’s in fact a $25m budgeted thriller telling a story on a scale that would usually require four times that. Light on action and heavier on plot, it might disappoint audiences expecting something bigger, which could explain the unusually late embargo for reviews, Focus Features perhaps hoping that word doesn’t spread too fast.

Facebook Twitter Pinterest In Captive State, Chicago residents deal with life under extraterrestrial rule. Photograph: Focus Features

Another, more obvious, reason for this is an awareness of just how messy so much of it is. While Sanders and Majors are both excellent as the film’s central siblings, the script can’t quite decide who to focus on and for a large unexplained stretch, Sanders simply doesn’t appear. They both add emotional weight but are required to do far too much of the heavy lifting with the script failing to flesh out their fractured dynamic. Similarly, Goodman is reliably strong but provides more than the film is willing to give him in return and is hampered by a structure that relies on a major last-minute twist. Wyatt, and co-writer/wife Erica Beeney, pepper the script with intrigue and misdirects to prepare us for the big reveal but when it arrives, so do questions, lots of them, and the film feels unequipped to answer them.

But logic aside, it somehow remains oddly likable. The plot might be overly convoluted but it’s not starved of nifty ideas and while characters might be underdeveloped, there’s a packed cast tasked with bringing them to life, also including an underused Vera Farmiga and a blink-and-you’ll-miss-it appearance from If Beale Street Could Talk breakout Kiki Layne. The film also boasts a standout sequence focused on a high-stakes mission that’s as involving as anything Ethan Hunt ever set his hands on and the aliens themselves are uniquely designed, scary and bewitching, as strange as the film within which they star.

Captive State is imperfectly constructed, at times frustratingly so, but it’s trying, doggedly, to do something different and given the bland efficiency of so many wide-releasing sci-fi movies, that’s hard to fault.