There's something deeply, deeply satisfying about watching Anne Hathaway playing a train wreck so obliviously selfish that she accidentally wills a rampaging kaiju into the world. Although I've never been among the Hathaway "haters" who've sneered over her perceived perfection or overzealous earnestness, it's still a joy to watch her go wild.

Again and again onscreen, she's charmingly transformed from awkward duckling to elegant swan in films like "The Princess Diaries," "The Devil Wears Prada" and "One Day." And off, she's dazzled on one red carpet after another, her lithe figure, flawless skin and dazzling smile proving ideal for an eternity of ornate, untouchable gowns. But Hathaway herself has repeatedly punctured this prim-and-prissy image, be it playing a tough-talking (and topless) cowgirl in "Brokeback Mountain," the drug-addicted black sheep of the family drama "Rachel Getting Married," the leather-clad and sharply heeled cat burglar of "The Dark Knight Rises" or her Oscar-winning turn as a destitute and desperate  single mother in "Les Miserables." Yet for all this, "Colossal" has the most fun with Hathaway, allowing the pristine ingénue to dig deep into irreverent humor and unhinged fantasy. And from this arises a quirky, captivating and career-defining performance.

Written and directed by Nacho Vigalondo ("Time Crimes"), "Colossal" follows thirtysomething screw-up Gloria, a professional blogger who's lost her way since being fired. Rather than searching for a new job, she spends her nights out drinking herself into oblivion, and her days hungover and disappointing her yuppie boyfriend (Dan Stevens of "Legion"). That is until he dumps her, pushing her out of their shared loft and back to her hometown to lick her wounds in her parents' empty house. She quickly reconnects with an old classmate (a perfectly cast Jason Sudeikis) who shares her love of snark and all-night drinking. Then she bumbles into the strange discovery that she occasionally manifests a towering monster over Seoul, South Korea.

Colossal

What if you learned your thoughtless actions actually had huge impact? Think the Butterfly Effect, except instead of a flapped insect wing causing an across-the-world tsunami, a drunkenly flailed limb shatters skyscrapers and rains rubble upon the bustling, beautiful metropolis. It's a sci-fi concept that's deliciously ludicrous, and Vigalondo's script plays out this discovery in smirking waves. First a bleary-eyed but horrified Gloria hears about the monster, hours after its first feckless rampage. Next, she's stricken and she begins to piece together the odd coincidence of its appearance and movements. Then, she recklessly invites her drinking buddies to see her incredible new party trick. And it's fun! Until the full weight of responsibility of kaiju control hits, as a stumble kills untold civilians. From there, "Colossal" spins from carefree comedy into something darker and sharper, spiked with surprises and rife with pleasures.

I'm aching to reveal more, but to spoil where Vigalondo's story spins would be a crime against cinema. So allow me to pivot. Hathaway is wondrous, warm and relatable as a grade-A screw-up. Her skin littered with random tattoos, her signature long flowing hair gnarled as if she'd dropped her hairbrush in the toilet and never bothered to retrieve it, her eyeliner only ever in morning-after smudge mode, she is damage personified (admittedly in a pleasing movie way). As crooked smiles crack across her face and fractured laughs burst from her lungs, Hathaway paints a portrait of a woman we've all met. Gloria is the girl who's great at parties, but who you flee from in daily life because she's damaged and damaging, rampaging on a human scale. But when that's blown up to Godzilla scale, something incredible shifts within her, although not right away. And in this sense, "Colossal" becomes a coming-of-age comedy like Jason Reitman's blistering and underrated "Young Adult," where Charlize Theron played an overgrown and festering mean girl. Shaken with the fizzy fantasy of city-tromping monsters, "Colossal" gives its rampaging antiheroine an earth-rumbling chance at redemption, in a climax that is inventive, wild, and deranged.

Simply put, it's sensational. "Colossal" is a film so strange it's very existence seems a miracle. America's Sweetheart sends up her prim persona in a low-budget monster comedy that is silly, satirical and stupendous. It's not just one of the best films out of the festival circuit, it's one of the best films of 2017.

"Colossal" screened Friday at SXSW. A theatrical release follows on April 7.