Add to the subgenre of musical comedies starring real-life groups — such as the Beatles (“Help”) and Tenacious D (“Tenacious D and the Pick of Destiny”) — the new film “The History of Future Folk.”

Never heard of Future Folk? A pop-bluegrass duo consisting of Nils d’Aulaire on banjo and Jay Klaitz on guitar, the pair play pleasing, jangling songs that grow on you with their exaggerated earnestness and wide-eyed drama. Oh, yeah, and d’Aulaire and Klaitz wear jumpsuits and orange bucketlike helmets in “History” that make them resemble extraterrestrial spacemen in the cheapest sci-fi movie ever.

That’s pretty much the gist of the low-key, charming “The History of Future Folk.” D’Aulaire plays Bill, a New York dad who is actually General Trius from the doomed planet Hondo. Sent to Earth with a weapon of mass destruction, Bill falls in love first with music and then Holly (Julie Ann Emery), whom he marries.

Bill’s Hondo origins are reduced to a bedtime story he tells his young daughter, Wren (Onata Aprile). But he is also living a secret life as Trius, trying to save Hondo through peaceful means while, incidentally, wearing his spacesuit and playing banjo in a club run by Larry (Dee Snider).

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No, nothing about this movie by co-directors John Mitchell (who wrote the script) and Jeremy Kipp Walker makes sense, and it only gets more complicated when Klaitz shows up as the Mighty Kevin, a feckless fellow Hondo-ian who becomes Bill’s partner in music and trying to save Earth.

But the nonsense proves good, goofy fun that works well because “History” at least acts as if it takes itself seriously, going easy on obvious ironies while dishing out catchy tunes. And talk about gritty: What could be more hard-core drama than a reptilian assassin who disables Bill but refuses to kill him because he wasn’t paid enough?

Tom Keogh: