FX’s ‘Black Narcissus’ poses a real mystery: What is this, and why is it on?

From its slick marketing materials (something FX has always excelled at), one might expect a scary thriller set in a convent in the Himalayan mountains. If you know about the novel (or have perhaps seen the 1947 film adaptation), you’d expect more of a psychological thriller threaded with forbidden desire. One might also tune in expecting an uplifting story of nuns starting a mission school where others have failed. It could also be about a crisis of faith. Too long to be a movie and too short to satisfy as a miniseries, this “Black Narcissus” dabbles in being all of the above, and, alas, doesn’t fully succeed at any of them.

But it doesn’t deserve a thumbs-down review, either. Thanks to some excellent and at times gripping performances — especially from its lead, Gemma Arterton — “Black Narcissus” remains intriguing while never quite getting to the point of riveting. Even when it drags, it’s still beautifully shot (a good bit of it on location in Nepal) and visually compelling. For at least an hour or two, that’ll do.

Arterton stars as Sister Clodagh, a disciplined young Anglican nun living in British-ruled India with the sisters of St. Faith. Clodagh receives orders from her superior, Mother Dorothea (the late Diana Rigg, in one of her last roles), to lead a group of sisters to a remote village in the Himalayas and open a convent school at Mopu — a hulking, former house of ill repute perched on a precarious cliff.

Mopu is owned by General Toda Rai (Kulvinder Ghir), who hopes the sisters will restore the compound and educate the local children, succeeding where other missionaries have mysteriously failed.

Clodagh and her sisters arrive to the daunting task of repairing not only the buildings, but mending cross-cultural relations with the locals as well. In the drafty and dark corridors, they are confronted daily with the building’s spooky past; the permanent housekeeper, Angu Ayah (Nila Aalia), stokes the weirdness as well their anxieties. “Black Narcissus” spends much of its time setting up ghost stories and hinting at spirit possession, and then not really delivering in that regard. The depressing atmosphere of Mopu, combined with the hard work and howling winds, takes its toll: Sister Clodagh becomes cold and preoccupied with her temptations (which she resists through self-flagellation), while the impressionable Sister Ruth (Aisling Franciosi) has turned into a self-absorbed brat.

What powerful influence has these women in such a state?

A man. He’s Mr. Dean (Alessandro Nivola), a sometimes friendly and sometimes aloof British expat, temptingly handsome in his vintage J. Peterman garb, who manages the nearby tea factory, lives in a cabin down the way and becomes the sisters’ trusted guide to everything from local customs to fixing the faucets.

As “Black Narcissus” slowly (too slowly) works its way to an anticlimactic froth, it’s disappointing to discover that it all comes down to two nuns going bonkers over a guy. (Fans of Nivola’s work, especially the 2005 film “Junebug,” may also swoon over Mr. Dean — especially when he barges in on Christmas Eve to drunkenly harmonize with the sisters’ staid rendition of “Silent Night.”) Sexism, along with a frustrating degree of repression (we can also call it chastity, if you like), should be expected when the source material is 80 years old.

Given that this is FX, however, one can’t help but wonder what this adaptation might have looked like with some zhushing from Ryan Murphy, or one of his acolytes. Give them a haunted mountain castle full of pent-up nuns and then stand back and watch the sparks fly. More needs to happen here, and it never does.

Black Narcissus (three episodes, about four hours) airs in its entirety Monday at 8 p.m. on FX.