The problem with The Nun isn’t that it’s one too many spinoffs of The Conjuring series, which has already spawned two installments in the Annabelle cursed doll saga. What’s holding it back is that the knuckleheads behind the camera have little concept for the basics of making a successful horror movie.

Working from a story co-credited to the fountainhead series’ godfather James Wan, the film features a perfectly fine, late-‘50s premise in which a nun hangs herself at a Romanian castle-turned-convent, long haunted by the nasty looking, habit-wearing figure that menaced Lorraine (Vera Farmiga) and Ed Warren (Patrick Wilson) in The Conjuring 2.

In response, the Vatican dispatches sorta-exorcist Father Burke (Demián Bichir, The Hateful Eight) and London-based novitiate Sister Irene (Taissa Farmiga, The Bling Ring) to investigate, and the sequence of events that follows suggests that seemingly qualified screenwriter Gary Dauberman, who penned both Annabelle movies and co-wrote It, merely cooked up outlines for spooky scenes and didn’t fill in the details.

Encountering nuns who probably aren’t real and other odd occurrences, Father Burke and Sister Irene — whose reason for being summoned to assist him takes too long to be revealed — walk into one supernatural situation after another and random things just sort of happen, rarely in interesting ways.

The poorly plotted events are further hindered by barely any sense for horror timing courtesy of music video director Corin Hardy, whose lone previous feature is the 2015 micro-budget horror film The Hollow. Fond of showing threats unseen by the protagonists then unsure what to do next, Hardy offers up plenty of opportunities for jump scares, but few are built up through creepy atmosphere and even fewer are acted upon.

It also doesn’t help that The Nun is one of those scary movies where the heroes are barely freaked out by the strange forces attempting to kill them — though, like many audience members, they may simply be too confused to be frightened.

A sequence that finds Father Burke following the spirit of a young boy he was unable to save from demonic possession and falling into a casket in a grave that shuts and suddenly fills with dirt is so sloppily enacted that its tension is a non-factor. One keeps waiting for him to wake up from a dream — psychological torment is teased throughout the film yet minimally developed — but his captivity is real and almost wholly ineffective.

Of the handful of moments that do work, the best arrive when it’s too late for The Nun to be redeemed. Foremost is a scene where local farmhand Frenchie (Jonas Bloquet, Elle) walks through a room of bloody hooded figures, a few of whose heads spin around to attention with a sickening crack, and there’s also some scattered eerie fun — and a rousing moment for French Canadians — in the insane, messy climax.

Still, it’s not these winning instances, but bafflement that’s likely to linger once the credits roll, including the casting of both Farmiga sisters. Their facial similarities and the narrative overlaps within the larger Conjuring universe suggest some purposeful connection between Sister Irene and Lorraine Warren, but like most aspects of this haphazard film, it’s probably just a simple case of nepotism.

Grade: D. Rated PG-13. Now playing at AMC Classic, Biltmore Grande and Carolina Cinemark

(Photo: Warner Bros.)