Eccentrics, preferably photographed in their shambolic houses and habitats, have been a documentary staple at least since the Maysles brothers’ batty 1975 exposé of Edith and Edie Bouvier Beale, “Grey Gardens.” With “The Monastery: Mr. Vig & the Nun,” which opens today at Film Forum, Pernille Rose Grønkjaer affectionately offers up a respectable Scandinavian entry: Jørgen Lauerson Vig, a never-been-kissed 82-year-old curmudgeon who invites the Russian Orthodox Church to turn his crumbling castle into a monastery.

Mr. Vig, a somber former parish priest, lives alone in the selectively furnished and heated edifice, with a half-naked cannabis farmer for a neighbor. Ready for framing in a national gallery of 19th-century naval generals, he has a long, wispy beard and wears a fur cap atop his long, severe countenance. Followed about by Ms. Grønkjaer, he’s stubborn, disarming, and, as the full scope of his solitary past emerges, somewhat pitiful.

His long-held dream moves closer to reality when the contingent of Russian nuns arrives, headed by the formidable Sister Ambrosija. During the course of their visits, with shades of a TV home-decorating makeover show, Sister Ambrosija politely but firmly requests that Mr. Vig make necessary roof repairs, install a new boiler, and remove the odd bachelor-pad holdover like a vintage opium-den bed. Down comes a Tibetan religious painting; up goes her gift for her fussy host, a religious icon.

Sister Ambrosija shows good-humored persistence in the face of Mr. Vig’s apparent need to be convinced point by point. He passive-aggressively whines that the castle is “a ruin” and maintains that she needn’t attend meetings about the building’s future since she doesn’t speak Danish. The meetings convene a “board” that appears to consist of Mr. Vig, his buddy, and an attending lawyer. But Sister Amborsija presses on, conversing with Mr. Vig in their common language, English.

The Sister and her nuns convert what looks like a dining-hall-turned-lodge-lounge into a church, installing a cross, icons, and other artifacts. As the nuns settle in, they adhere to a daily prayer schedule and sing with unexpected beauty. Amid this burgeoning spiritual ambience, Mr. Vig blithely suggests moving the church during renovations, and it’s amazing that Sister Ambrosija can respond as coolly as she does. (Relocation is impossible once the structure has been ordained.)

Mr. Vig emerges as a self-proclaimed “narrow” mind who has, to some extent, simply avoided the world at large, though we don’t learn where all those years have gone. Deeply affected by his father’s death, he still ruminates over the day he flubbed kissing his mother goodbye. With regard to women, or “women’s secrets,” he “stays out of it.” He theorizes he might have been led astray by his complex about imperfect noses, one of many glimpses at obscure little systems of reasoning that flirt with nuttiness.

Despite this confounding history, the give-and-take between Mr. Vig and the nun is what captivates Ms. Grønkjaer, but she’s all too eager to nudge her documentary in the direction of gooey separation and reunion between the two. The filmmaker must have faced considerable obstacles in wrangling Mr. Vig, who even inserts a snide rider into his contract with the Russian church solely in the spirit of provocation. But her touch comes to feel too light, leaving too much unexplained and unexamined (like Mr. Vig’s odd ambition to get unpaid labor out of the nuns).

Still, she does capture the priceless scene of Mr. Vig and Sister Ambrosija hovering over a word processor and arguing over the contractual arrangements for handing over the castle. The spectacle of a headstrong grump flexing his last bit of leverage over nuns subject to his whim is a hilariously petty footnote to the vast history of organized religion in Europe. But “The Monastery” ends mercifully on a note of spiritual optimism, suggesting that beneath Mr. Vig’s crabby exterior is a lost soul in search of rest.

Through September 11 (209 W. Houston St., between Sixth Avenue and Varick Street, 212-727-8110).