Filmmaker Nacho Vigalondo’s fourth (and perhaps most openly accessible) feature effort Colossal is one of the most inventive giant monster movies I have ever seen. It’s also one of the most painfully heart-wrenching and clearly realized allegories for the nature of addiction ever committed to screen. It’s essentially Malcolm Lowry’s “Under the Volcano” simultaneously set in two parts of the world with kaijus and perplexed millenials. It sounds silly, but emotionally, Colossal packs an undeniably powerful punch. It’s just a shame that one little bit at the end kind of sucks the wind out of its sails. Not enough to dampen any good will towards the film, but something that reminds me in unflattering ways of Vigalondo’s previously wonky efforts.

NYC trainwreck Gloria (Anne Hathaway) has just been tossed out of her loft by her increasingly impatient, but loving boyfriend (Dan Stevens) for her hard partying, unmotivated, flighty, flaky ways. With nowhere else to go and barely any true friends that can help her out, Gloria makes her way to a dormant vacation property owned by her parents in suburban Maine. Desperate to make ends meet, she takes a gig working as a bartender at a place run by Oscar (Jason Sudeikis), a former childhood acquaintance who still lives in town. Together, they stay up all night partying and chatting until one early morning after a hard night out, Gloria notices something strange. If she walks through a seemingly innocuous playground at 8:05 am, across the world in Seoul, South Korea, a giant monster will start attacking the city. Well, not so much “attack the city” as “ape everything Gloria does,” but it still causes plenty of destruction and weighs heavily on Gloria’s conscience.

That’s about all I want to give away about the plot of Colossal, and I fear I might have said too much already. But while I might have spoiled in some small way the mysterious affliction Gloria suffers from, I haven’t spoiled writer-director Vigalondo’s greatest swerve, which comes just before the film’s halfway point. That twist in an already somewhat surreal story makes Colossal even more resonant. While the idea of a woman halfway around the world controlling the actions of a hulking monster in Asia is a pretty great hook for any sci-fi comedy, Vigalondo has the guts, fortitude, and perfectly capable cast to take things in a welcome, serious direction.

While the idea of a monster capable of flattening an entire city in the same manner as a drunk falling down is in and of itself a pretty easy metaphor to make, Colossal concerns itself more with depicting the patterns of repetition that most addicts experience. To get personal for a moment, I am the son of a pair of alcoholics, and I can say that as written and depicted by Hathaway (delivering her nerviest and best performance since Rachel Getting Married), Gloria’s actions and attitude ring true across the board. There’s something palpable about how Vigalondo, Hathaway, and Sudeikis (who has never been better) are able to tell a story of people who think they’re in control and that they’ve learned important life lessons, but who still stubbornly make the same mistakes because of their slavish adherence to their vices.

At a certain point in Colossal, viewers will question Gloria’s actions and why she continues to go back to the same triggering and troublesome places all the time. The answer is because she has become unable to function without such triggers. At the start of the film, Gloria isn’t a nice person to be around, but as the toxicity of the environment around her begins to metamorphosize into something even more loathsome, it’s impossible not to feel and root for her. Vigalondo, Hathaway, and Sudeikis handle everything with a healthy dose of often uproarious humour (a riff on the popular YouTube “Thug Life” videos is outstanding), but the dramatic beats energize the film more than the monsters and gags. It’s a film where the audience will question why Gloria does what she does, but the sad, truthful answer is because those actions are all she knows. It also depicts how addicts are more prone to becoming victims and purveyors of violent acts, something else I sadly relate to all too well.

It’s just a shame that headed into the climax, Colossal starts to strain a bit under the weight of sometimes all to convenient plotting and a dénouement that strikes as frustratingly illogical in the face of everything else Vigalondo has set up in terms of his story’s dynamics. It’s further frustrating because each of his previous features (Time Crimes, Extraterrestrial, Open Windows) suffer from the same problem. Vigalondo puts a lot of thought and effort into his first and second acts, and barely any attention to the final act, preferring instead to send things out on the “coolest” note possible instead of the most logical or thoughtful one. It’s maddening that this has become an official calling card of an otherwise talented and stylish filmmaker. Colossal, however, is unquestionably his best and most balanced work on the whole, but I really hope he learns how to end a film in the near future.