The movie equivalent of not judging a book by its cover is not judging a movie by its central premise.

The movie equivalent of not judging a book by its cover is not judging a movie by its central premise.

The central premise of “Copenhagen” is, well, squirmy, but movies have risen above that before (see the recent “Wetlands,” one of my favorite movies of the year). This one generally does, though not far enough for greatness.

William (Gethin Anthony of “Game of Thrones”) is a 28-year-old American traveling Europe with his friend and his friend’s girlfriend. A falling out with his friend leaves him alone in Copenhagen, Denmark, as he searches for a lost relative.

He meets Effy (Frederikke Dahl Hansen) in a café, and after a contentious introduction, the two end up on an adventure through the city. Romance is in the air … until William learns Effy is 14 years old.

Writer-director Mark Raso and actor Anthony establish William as young man who lacks maturity, a young bro abroad learning about life beyond bro-hood. Hansen — actually 20, but looking every bit the age of her character — is the savior, giving the complex performance that the premise needs.

“Copenhagen” plays out like “Before Sunrise” if one of the central characters was too young. Even when it is sweet, it’s hard to break the creepiness of that. It’s an intriguing film, but I wonder if it wouldn’t have worked better if the two characters just became friends (which can actually happen).