Violins tremble in the early minutes of Nacho Vigalondo's monster comedy Colossal as a Manhattan apartment braces for the worst: Gloria (Anne Hathaway), a disgraced blogger and a drunk, stumbling through her boyfriend Tim's (Dan Stevens) doorway with yet another sour-breathed excuse for why she's come home at breakfast. Her roar is a babble of nonsense: After the bar closed, she got stuck at Georgia's — no, wait, Natasha's. Once she believes she's scared up his forgiveness, Gloria caps her rant with a fatuous giggle, the party-girl equivalent of Godzilla's burp.

No need to call the National Guard: Tim's already packed her bags. By the title card, Gloria's fled to her rural hometown, hiding that tail between her legs under desperately hip parachute pants. Her asymmetrical leather jacket clashes with the locals' flannels, but that's fine. Gloria is the kind of good-time flirt who conquers a room to distract herself from admitting she's lost everything else. And though there's a real monster terrorizing Seoul, a giant, hairless thing that looks like a 700-foot boiled cat, we spend Colossal with our human beast, who obsesses over videos of South Korea's wreckage. In Gloria's bloodshot, hungover eyes, we see her horror and her empathy: What did I destroy last night?

Colossal isn't one of those inspirational farces in which a city girl gives up her heels to heal herself in her childhood Hicksville. Most movies with this framework offer up a standard rom-com diva who turns into a sunshiny beauty with a slap of mud, usually courtesy of a hunk in denim. And sure enough, there's a handsome bachelor with a pick-up truck: Oscar (Jason Sudeikis), who treats Gloria like a touring rock star. He immediately offers her a ride, and a television, and a futon, and a job at his bar, showering her with bounty as though her rider demanded them. Supposedly, he and Gloria were classmates, though Sudeikis and Hathaway's seven-year age gap defies realism, even in a movie in which a Gorgon disco dances.

But Vigalondo's script doesn't believe in saviors. He's attuned to the ways nice guys — and Nice Guys™ — try to tame their crush by saddling her with attention, while never giving a girl the freedom to refuse. Besides, he barely believes Gloria can save herself, or even wants to try. She's a different kind of bitch than the ones we usually see onscreen. She's not heartless; she's thoughtless. She insults people without noticing. When Oscar first spots her on the road and immediately squeals to a stop, Gloria shrieks, “I can't believe I recognized you!” Gee, thanks. He remembers everything about her. Later, at the family bar that Oscar's upgraded into his imagination of urban cool, she beams that he shouldn't have bothered. Its old look, the country kitsch he's worked so hard to modernize, is “actually ironic now!”

Slowly, we realize that what other movies would sell off as a winning romance is actually a toxic combination: a passive-aggressive nobody and a narcissist who tramples over his feelings. His male friends, dopey Garth (Tim Blake Nelson) and timid Joel (Austin Stowell), aren't any stronger. Surrounded by glass-paned egos, Gloria can do real damage. Especially when Oscar would kill to have some of Gloria's careless but powerful magic.

Gloria can manipulate men with her bewitching smile, yet Hathaway knows Gloria's charm is fading. She hints at the future has-been who's just a few years ahead, a shaggy, mascara-smudged alcoholic whose body, made lumpy in deliberately unflattering shirts, is already starting to sag. Every morning, she wakes up in pain — partially from her deflated air mattress — though, tellingly, she never tries to make it or anything else work. She's prematurely accepted her bad fate, the cricks in her neck that won't ever go away. I've known women and men like her, many of whom have yet to turn things around. Once a month, I worry I'm one of them, and I suspect Vigalondo knows them, too. At film festival parties, I've seen him jump on tables, kicking beer bottles like piddling skyscrapers. Bless his mess. He gets that being fun is fun. Colossal has no patience for piety or punishment. Even when Gloria gets punched in the face, the film refuses to sob. Instead, it's oddly heroic.

Hathaway must be thrilled to have her best showcase in years. She commits to roles like a boozehound ordering a row of shots, even when the parts don't deserve her. They often don't. Hollywood looks at her fervency and sees a valedictorian to destroy, or at least shame into taking love tips from Robert De Niro in perfect priss-punishers like The Intern, and audiences have absorbed it, too. Her zeal is intimidating, and her earnestness can seem embarrassing when we prefer our stars to act like they tumbled out of bed and into the spotlight. I love her in this, especially the way Hathaway's Gloria never apologizes for being herself, at least not sincerely. Instead of making teary amends, she and everyone else in the film toss off weak apologies that, eventually, sound like insults themselves.

Gloria alone makes Colossal unique. Still, the selling point is how writer-director Vigalondo connects this dramedy about humans with monstrous emotions — jealousy, snobbery, selfishness, repressed rage, all the things that used to guarantee you'd grow a hairpiece of snakes — to solemn newscasts about the sci-fi massacres in Seoul. The mash-up doesn't quite fit, and the more Vigalondo explains the logic, the less his halves glue together. Yet the movie makes sense in our guts, or really, our reptile brains. I wonder how conscientiously Vigalondo picked the South Korean capital because its homonym is “soul”? And I can't help but suspect that paralleling the deaths of hundreds in Asia with the squabbles of a few sulky Americans, the exemplar of White People Problems, is the Spanish filmmaker's self-aware sour joke. If that makes Colossal a prank, it's likely the best one you'll see all year: an artisan mousetrap, an organic raspberry blown at the audience, a fly in your ice cube when, like Gloria, you need a stiff drink.