In last year’s fantasy masterpiece A Monster Calls, the Spanish director Juan Antonio Bayona gave us a young British boy wrestling with grief and anxiety, metaphorically realised in the form of a gigantic walking tree. Here, Bayona’s countryman Nacho Vigalondo serves up an impressively bizarre genre hybrid in which a young American woman’s drunken binges manifest themselves as a monstrous, lizard-like creature that terrorises South Korea.

Lashing together disparate tropes from quirky US indie-romances and old-school Japanese monster movies (think Rachel Getting Married v Godzilla), the uneven yet fitfully funny result plays like a Noah Baumbach remake of the rehab dramedy 28 Days crossed with Guillermo del Toro’s Pacific Rim. It sounds like a disaster waiting to happen, and there are many moments when Colossal threatens to collapse like the buildings crushed beneath the gigantic monster feet. But against the odds, Vigalondo keeps us invested in this tragicomic parable about the destructiveness of addiction, the hangover of remorse and the horrors of domestic abuse. With jokes. And giant robots. Really.

Anne Hathaway plays Gloria, an online journalist who has blotted her virtual copybook and now drinks to fill the hole where work should be. “The only time I get to see you is when you’re hungover,” says soon-to-be-ex-boyfriend, Tim (Dan Stevens), an Englishman in New York who packs Gloria’s bags and shows her the door. Scurrying back to an empty family home in the dead-end town of her youth, Gloria meets childhood friend Oscar (Jason Sudeikis) who runs the local bar and spends evenings boozing with gormless sidekick Garth (Tim Blake Nelson) and handsome toyboy Joel (Austin Stowell).

One morning, as Gloria shambles home through a lonely children’s playground, a gigantic “kaiju” materialises in Seoul, wreaking havoc. After much nervous head-scratching, Gloria concludes that she is somehow controlling this beast. Is she a delusional paranoiac? Or are her personal problems being played out in super-size fashion, with catastrophic results?

Having first made his mark with the Oscar-nominated short 7.35 de la Mañana, writer/director Vigalondo scored cult hits with his first two features: the looping, low-budget weirdie Timecrimes (2007) and Extraterrestrial (2011), a dysfunctional romcom with UFOs that earned him the title “the Woody Allen of science fiction”. Colossal began life as a Spanish-language script that Vigalondo had originally intended to shoot as a cheap experimental Euro-pic. But a barnstorming performance by Anne Hathaway has opened it up to a wider audience, albeit one that may be utterly baffled by a movie in which the real monster turns out to be a bottle.

From Tim’s early declarations that “you’re a mess – you’re out of control!” to the guilty awakenings that plague Gloria (“What did I do? How many people did I kill?”), Vigalondo’s script maintains a sharp balance between the down-to-earth disasters of her drinking and the out-of-this-world chaos playing on the TV news. Crucially, the monster “never looks down”, apparently oblivious to the carnage it leaves in its wake. There are satirical swipes, too, at the spectator culture of rolling news; when Gloria worries about “all those innocent victims” on the other side of the world, Oscar replies that it makes you realise “how lucky we are to be watching”. Elsewhere, it is pointedly observed that “if it only attacks Seoul, people will stop caring”.

Facebook Twitter Pinterest ‘Genuine pathos’: Anne Hathaway in Colossal. Photograph: Allstar/Voltage Pictures

Hathaway does a great job of making emotional sense of the film’s warring elements, her teased fringe and teen-goth wardrobe suggesting an arrested adolescence to which she brings genuine pathos. Hats off too to Sudeikis, who slips almost imperceptibly from apparently harmless man-child (“You wanna hang out?”) to embittered, controlling bully – two sides of the same self-loathing coin.

Amid the increasingly dark, character-driven comedy, Vigalondo is at pains not to shortchange the supernatural elements, conjuring sparse but effective creature-feature visuals that combine the playful fantasy of Ghostbusters with the “found footage” grit of Cloverfield, all on a reported budget of only $15m.

Meanwhile, in the US playground sequences, cinematographer Eric Kress keeps Hathaway in the foreground, wittily magnifying her size to mirror the spectacle in Seoul. A dextrous score by Bear McCreary helps negotiate the alarming tonal shifts, but in the end it’s Hathaway who holds it all together, even as her on-screen life falls apart.