Equal parts funny and forlorn, with a smattering of the violence that always been a sort of Emerald Isle background noise, “The Banshees of Inisherin” is Martin McDonagh’s most Irish film, because it’s a lot like Ireland itself.

Set in isolation, on a treeless island off the Irish coast in the Civil War year of 1923, this parable is about an inexplicable feud that all involved are just going to have to live with, even if its cost is grim self-mutilation and loss. What could be more Irish than that?

The playwright-turned-filmmaker of “Three Billboards Outside Ebbing, Missouri” rounds up his “In Bruges” muses Colin Ferrell and Brendan Gleeson for a story that goes back to troubles before “The Troubles,” which the “Seven Psychopaths” filmmaker has hitherto only addressed on the stage (“The Lieutenant of Inishmore,” etc.).

That brief Civil War during the founding of the Irish Republic is close enough for the folks on Inisherin to hear the rattle of rifle fire, the crackle of firing squads and even glimpse at a distance as smoke arises from explosions. It’s not necessarily the theme of this story, but it’s never far away and near enough to feel, if not involve oneself with.

The distance, the blur of 20th century history that informs the viewer makes Irish history seem like one long feud, one violent period indistinguishable from the next, and entirely arbitrary in the fog of memory.

That’s a word Pádraic Súilleabháin (Farrell) may not be able to summon up — “arbitrary” — when he stops down’ta J & J Devine’s Public House for a pint with his mate, Colm Doherty (Gleeson). He’s already tried to fetch the man from in front of his Victrola in his solitary seaside cottage. He’s already wondered to his sister Siobhan (Kerry Condon of “Three Billboards” and “Better Call Saul”) what’s up.

“Have y’been rowing?” “I don’t tink we’been rowing.”

But the pub confirms, in a public setting, what his bookish sister guessed.

“I just don’t like you no more,” the grizzled old redhead growls.

There are no “Banshees” on Inisherin. But if there were, poor pushover Pádraic would ask, badger and beg them for a reason this has happened. Because he bends the publican’s (Pat Shortt) ear, annoys his sister with his persistence, expects answers from the perpetually clueless Dominic (Barry Keogh, of course) and simply will not let the matter drop with Colm, whose many rebuffs let out specific gripes — starting with “aimless talk,” “nice” used as an insult for the insipid, and zeroing in on “feckin’ stoooopid.”

And if Pádraic doesn’t stop with the questioning — of Colm, the priest and everybody else in the village — the ginger fiddler lets him know that he’s going to start lopping off fingers. Not Pádraic’s, but his own.

That’ll show him.

McDonagh is a filmmaker whose movies are always firmly grounded in a sense of place. This film, which started life as the final third of an Aran Islands (stage) trilogy (the aforementioned “Lieutenant of Inishmore” and “The Cripple of Inishmaan”) was filmed on Inishmore, just off Galway on the west of Ireland.

We’re immersed in a world of ancient loose-stone fences separating scores of tiny grazing fields, of modest, tidy houses with no electricity where pets and livestock — Colm’s faithful and very smart dog, Pádraic’s miniature donkey (a scene stealer) — practically have the run of the place.

Mrs. O’Riordan (Bríd Ní Neachtain) doesn’t just traffic in groceries at her general store. She requires gossip as a gratuity. The priest (David Pearse) may come over from Ireland proper for services, but he’s up to date on Colm’s state of mind thanks to the confessional. And nobody likes the local constable (Gary Lydon), Dominic’s dad.

McDonagh brings Irish music into the mix, with Colm’s circle of players joined by eager students of “diddley aye” music from the Irish traditional music mecca of Lisdoonvarna.

And the performances are uniformly fine, with Farrell great at conveying a sort of stupefied, unconsidered guilelessness and Condon providing the film’s “feckin'” fire.

What our playwright/filmmaker doesn’t manage to any great degree is tying all this — directly or clearly — to a larger theme. I’m sensing the eternal and essentially pointless nature of Irish strife, the feuds that will not die and yet serve their purpose, at least in the national soul. But it’s not crystal clear that’s what McDonagh had in mind.

As he drifts into the grisly consequences of this “don’t want to be friends no more” ghosting, we’re reminded of the repellent violence that has been this “dark comedy” specialist’s trademark, and that the brilliant Martin’s never spelled his “message” out as clearly as brother John Michael McDonagh did in his films “The Guard” and “Calvary.”

That said, the “troubles” subtext is as good as any other to hang onto while following our favorite Irish filmmaker into the myopic abyss of Ireland’s romanticized past, an “Unquiet Man” showing us the good, the bad, the green and the diddley aye that shaped our perceptions of the place forevermore, when violence was always a part of a more accurate picture.

Rating: R for language throughout, some violent content and brief graphic nudity.

Cast: Colin Farrell, Brendan Gleeson, Barry Keogh, Gary Lydon, Pat Shortt and Kerry Condon.

Credits: Scripted and directed by Martin McDonagh. A Searchlight release.

Running time: 1:49