It is hard to pull off a story as strange as “Colossal,” in which a self-destructive alcoholic woman accidentally triggers the appearance of a giant monster, and this film does not consistently succeed, but it is nevertheless riveting, challenging, unforgettable and very funny. Stars Anne Hathaway and Jason Sudeikis are fantastic and it’s a worthwhile experience to see two actors keep the viewers from rooting for them. Everything about this freaky little flick is unusual.

Anne Hathaway stars as Gloria, an unemployed writer living in New York City whose out-of-control drinking leads her boyfriend Tim (Dan Stevens) to kick her out of his apartment. This film gives us no straight good guys from the first scene — while Gloria’s behavior is certainly wrong, Tim is rather unfeeling and totally uptight. With nowhere else to go, Gloria heads to her empty childhood home in upstate New York, where she runs into an old school chum, Oscar (Jason Sudeikis.)

Oscar seems like a nice fellow who owns his late father’s bar, which is perfect for the hard-drinking Gloria, but after a night spent blackout drunk, Gloria wakes to a horrifying global news story: a huge Godzilla-esque monster has appeared in Seoul, South Korea, and killed hundreds of people. (Very) improbably, Gloria discovers she is connected to this monster’s appearance, and once she convinces Oscar and her other new friends of the connection, things get even weirder.

At odds with a cheesy monster premise is the story of the relationships between these terribly damaged, and basically just terrible, people. The many drinking scenes are very tightly written and portrayed. With an excellently controlled pace, this becomes a well-observed drama of abusive personalities that would stand alone without the monster elements. But of course, when you have this understated relationship drama that intersects with a low-budget monster film, you get the kind of movie Spike Jonze might have written.

“Colossal,” however, is more emotionally accurate but less inventive than one of a Jonze’s classics, and this film’s director, Nacho Vigalondo, fails to create and unite wildly disparate and fanciful plot elements with the genius of Jonze. Vigalondo himself described his film as “Being John Malkovich” meets “Godzilla.” This is an apt description, but “Colossal” has different strengths and weaknesses.

The arcs the characters take are almost as surprising as the appearance of a monster in Seoul, and the explanation slowly doled out deepens not just the plot but our understanding of the allegory we must come to realize is at work. There are, however, no easy answers. “Colossal” isn’t perfect but it is certainly intriguing, and it’s certainly worth watching. Even with its problems, it is still more fun to watch and think about than many smoother but less ambitious ideas on film.

The painfully realistic characters created by Hathaway and Sudeikis are the most remarkable elements in a film full of remarkable elements. Like its flawed protagonist, “Colossal” is imperfect, but it is also a peculiar experience well worth your time.

“Colossal” is currently available to rent.