Opening this Friday at the Coolidge Corner Theatre, James Demo’s absorbing documentary “The Peacemaker” boasts plenty of local flavor but also dips into such international hot zones as Israel, Iraq and Nigeria. What begins as a chronicle of a man on a mission, resolves into an intimate portrait of a complex, yet resolute soul who’s gone through a series of life altering transitions — some of which, are none too palatable.

The peace negotiator of the title and man in question, Padraig O'Malley cuts a striking figure. Tall, lanky and in his mid-70s, he’s blessed with a handsome square countenance and steely blue eyes. If there was a casting call for intensity, O’Malley would be exactly what they’d be looking for.

While O’Malley calls nowhere home, he has a multitude of distinguished ties to the Hub, most notably as a professor of peace and reconciliation at UMass Boston. He's also the owner of the popular Cambridge watering spot, The Plough and Stars (his brother Peter and DeWitt Henry launched the revered local literary journal Ploughshares out of it in the '70s).

That’s more than enough to occupy most folks’ time, but not the globe-hopping O’Malley who has embraced conflict resolution in divided societies as his life's work — a tireless pursuit that takes him to some pretty unsavory places and often puts him in harm’s way. For one such mission, O’Malley had to covertly tote a suitcase full of money through the streets of Iraq to help get a diplomatic action off the ground.

Early on, we realize the irony of how a man so drawn to conflict is in fact a man living in conflict himself. If not from the clear unrest behind his eyes, then perhaps the revelation that as a recovering alcoholic, O’Malley manages a bar (and leverages its resources for his mission).

Born in Ireland, O’Malley came stateside as a scholar and promptly bet his Fulbright scholarship on the 1971 Ali-Frazier fight. He lost. Then in 1975, he brought opposing sides of the Irish struggle to Amherst for his first peace conference. He tapped the Plough for ample mood lubrication, which O’Malley says was critical to the negotiation process. It was also during this time O’Malley admits he was drinking his life away, philandering and getting into some bad situations.

The film documents how Alcoholics Anonymous ultimately becomes something of a model for O’Malley and his mission. “Just as AA works on the principle that one alcoholic is in the best position to help another,” he says, somberly, “one divided society is in the best position to help another.” In 1997, working with Nelson Mandela, he brought the fractious parties of Northern Ireland to South Africa to meet and share lessons learned about moving forward after Apartheid. O’Malley and Mandela subsequently became fast friends and allies.

To capture O'Malley fully, Demo tailed the backroom statesman for more than seven years, including excursions to the Middle East and Africa. Through "The Peacemaker" you can’t help but to become in awe of how tireless O’Malley is and how extensive his reach must be to get such key players from opposing sides in the same room. The bigger canvass work impresses and rightly so, but it’s the portrait of O’Malley stateside and in his personal life that ultimately becomes the more compelling aspect of the film.

There’s an incredibly touching and telling moment as O’Malley shares an ice cream with his adopted South African daughter. Then there’s the insight from one of O’Malley’s many former girlfriends who now serves as his personal assistant and O’Malley himself, who starkly proclaims that he doesn’t love anyone or anything but his work. A quick pop back over to a sweltering Plough, where the AC has gone out, and we get the manager and fractional owner of the bar grousing about O’Malley’s removed management style and raids on the cash register to fund his foreign missions. It’s a telling moment that fills in the edges.

One of the essential keys to the film's slow, entwining charm, beyond O’Malley’s intoxicatingly idiosyncratic personality, is the effusive patience demonstrated by Demo. An attorney by trade, Demo traded New York for Boston to pursuing his passion for filmmaking about a decade ago. Like the great Frederick Wiseman, there’s absolutely nothing intrusive in his style or approach. Whether it’s in O’Malley’s cramped Cambridge apartment, a conference room full of envoys with ears encircled by translation devices or an AA meeting, Demo just hangs back and observes, waiting for the moment to come to him.

As the narrative builds, Demo’s camera gets closer to its guarded subject and the film’s whole texture becomes increasingly intimate and internal — you can almost feel O’Malley’s heart beat. Toward the end, as O'Malley fears the prospect of Alzheimer’s slowing him down, he doesn’t worry so much about his health as he does about his work. And that says it all.

So the next time you hoist a pint at the Plough, know that some of your beer money might just be going to help save the world. Cheers.

"The Peacemaker" premieres on Friday, April 13 at the Coolidge Corner Theatre in Brookline.