In 1952, news of the apparent suicide of a nun at a cloistered abbey in darkest Romania reaches The Vatican.
They call upon one of their elite 'miracle hunters', Father Burke (Demian Bichir), to investigate, as the abbey has a 'chequered' reputation.
He is paired up with a young novitiate, Sister Irene (Taissa Farmiga), that the Church feels may be of assistance to him because of her history of "visions".
Arriving in Romania, the holy duo meet Frenchie (Jonas Bloquet), the French-Canadian courier and guide who discovered the body of the dead nun, and recruit him to their cause.
Together this threesome probe the mysteries of the haunted abbey, and try to get to the bottom of the site's unholy - and demonic - secrets.
To all intents and purposes, the set-up and plot of The Nun is a grand Dungeons & Dragons adventure, with three mismatched adventurers plunging into a 'dark underworld' of tricks, traps, and monsters (complete with a demon-warding holy relic) to try and solve a puzzle.
As a rule, I'm not a big fan of either prequels or jump scares, but as the latest entry in The Conjuring Universe of movies, the film cleverly weaves itself into the backstory of The Conjuring 2, by providing a kind of 'supervillain origin story' for the titular demonic Nun (again portrayed by Bonnie Aarons) aka Valac.
As to jump scares, there are only really a couple and they're handled surprisingly well, delivering cathartic releases from moments of escalating terror.
Directorial tools such as foreshadowing and atmospheric lighting are quite on-the-nose, but help give The Nun a pulpy feel that mixes elements of modern movies with those of the classic Hammer era.
Once our heroes are entrenched within the confines of the abbey, the story quickly devolves into a surreal rollercoaster of mental torments and ghostly visitations.
It's not worth trying to attach too much logic to much of what unfolds, instead wallow in the psychological torment of the main characters as they battle the evil forces at work within the abbey.
However, for all the smoke and mirrors, the script is intriguing enough that its real power is to compel you to want to rewatch both it - to catch what you missed the first time - and The Conjuring 2 to see where the two stories intersect.
There's also the nice meta-connection that Sister Irene is portrayed by the younger sister of Vera Farmiga who plays Lorraine Warren in the main Conjuring flicks, and has a couple of brief cameos here in some 1970's scenes lifted from the previous movie.
Ultimately, it's not required viewing, and isn't that informative on Valec's backstory, but is an entertaining funhouse flick with quite an old school vibe to it.