In what feels like the extremely long 90 minutes that it takes to wend your way through “The Little Hours,” we’re supposed to — accordingly to a mention at the beginning — recognize it as being based on “The Decameron.”

Full confession: I never made it all the way through the sexually charged Boccaccio book when it was assigned reading in college. But what I do recall from it doesn’t have much to do with what happens onscreen here. Oh, it takes place in mid-14th century Italy, and there are lots of nuns running around, all in various states of unhappiness, and a great deal of randiness is on display.

But despite an intriguing cast, most of which comes from a mixture of art house and television actors along with standup comics, the film comes across as an exercise in crassness. It’s an idea that likely didn’t make a lot of sense on paper, and simply doesn’t work, even as a spoof of a well-known, but rarely read, piece of literature.

It centers on a trio of nuns in a rural convent: Sister Alessandra (Alison Brie), who was unceremoniously dropped off there by her father; Sister Genevra (Kate Micucci), who seems lost and confused; and Sister Fernanda (Aubrey Plaza), a nasty woman who could embarrass a sailor with her language.

The place is run by the frustrated and usually drunk Father Tommasso (John C. Reilly), who has no qualms about dipping into the sacramental wine, and by Sister Marea (Molly Shannon), who has an agenda that isn’t even hinted at till near the film’s end. Thrown into this gaggle is Massetto (Dave Franco), a rapscallion who’s on the run from the husband of the woman he’s been fooling around with, and who, through an act of kindness, is given sanctuary — but only if he pretends to be deaf and dumb — at the convent.

And so the sexual rompings begin. This shouldn’t be a surprise. The sisters are all lonely, miserable, hungry, and tired of the daily routine. Suddenly there’s a strapping fellow, with an eye out for any women, among them. This could be fun. But even though most of the actors give good, freewheeling performances, and try to make everything fit into the realm of broad farce, writer-director Jeff Baena (“Life After Beth”) can’t seem to control his urges to let everyone go overboard, sometimes in zaniness, mostly in cursing.

The one stand-out, and not in any sort of good way, is Aubrey Plaza, who makes her Fernando loud, obnoxious, and vulgar, but not funny. At the other end of the spectrum, in the film’s single winning performance, is Fred Armisen as the ridiculous Bishop Bartolomeo. Armisen brings the character right to the edge of the top but manages not to go over it.

So, let’s see, we’ve got philandering, witchcraft, lesbianism, nudity, hysteria, drug use (don’t worry, it’s only belladonna), and a tad of violence. There are definitely some funny moments, but most of them are uncomfortable to watch. It’s really difficult to imagine who the intended audience is. It’s a film that needs a great deal of reining in, just to make it palatable.

— Ed Symkus writes about movies for More Content Now.

“The Little Hours”
Written and directed by Jeff Baena
With Alison Brie, Aubrey Plaza, Kate Micucci, Dave Franco, John C. Reilly, Molly Shannon
Rated R