Hailed before its release as “the most terrifying movie this year”, The Nun is a holy mess that will probably make an ungodly amount of money.

The fifth instalment in The Conjuring’s horror franchise, the film pulls out every hoary cliche in the scary movie toolbox. But flat performances, further hobbled by a leaden script full of expositional clunkers, will not damn it.

Opening simultaneously in the US and Australia this week, it’s on track for a stonking US$40 to US$50 million haul domestically on a budget of around US$22 million.

By far the most terrifying things about it are the poster art and makeup job done on beautiful Bonnie Aarons as the demonic Valak, first unleashed on an unsuspecting London family in 2016’s The Conjuring 2.

But director Corin Hardy is probably on a winner, thanks to an audience thirst for gothic horror, no matter how unscary.

The 2013 original, directed by Australian James Wan and starring Vera Farmiga and Patrick Wilson as real-life paranormal investigators Lorraine and Ed Wilson, was an unexpectedly enormous hit.

It accrued $319.5 million worldwide on a similar budget to The Nun.

Introducing Valak, the 2016 direct sequel took roughly the same on twice the budget. Freaky doll prequel Annabelle, roundly bashed by critics in 2014, nevertheless made $257 million globally on a teeny $6.5 million budget.

The ‘Valak’ character first appeared in James Wan’s The Conjuring 2.

Last year’s Annabelle: Creation fared much better with critics and at the box office, scoring $306.5 million from a $15 million price tag.

In other words, clunker or not, this series has an embedded, invested audience and is here to stay.

The Nun starts spookily enough in a bomb-damaged Romanian abbey in the aftermath of World War II.

Unleashed from an inconvenient hell mouth, Valak slaughters one nun while another takes her own life, leaping from a tower window with a noose around her neck in order to escape possession and eternal damnation.

Sometime later, a French-Canadian import dubbed ‘Frenchie’ (Jonas Bloquet, actually Belgian) discovers her crow-pecked body and raises the alarm.

That brings one of the Catholic Church’s top paranormal investigators Father Burke (Demián Bichir), teamed with Sister Irene (Vera’s younger sibling Taissa), a novitiate troubled by dark visions and yet to take her vows.

Despite the obvious familial resemblance between Irene and Lorraine, The Nun is pretty vague about whether there’s an in-film connection.

Sister Irene, played by Taissa Farmiga.

In fact, it’s pretty vague full stop. If you’re looking to find out more about the origins of Valak, there’s very little here beyond some hokum about an evil duke whose plans are stymied by medieval crusaders.

Even if there was more backstory, therein lies the problem. Horror, by its very nature, is at its strongest when it taps into our primal fears.

For that to work, we have to feel invested in someone to be terrified for. Scary movies that focus on the monster, as opposed to the struggling heroes, are already on the back foot.

Add in too much computer graphic nonsense and it tends to hobble the menacing potential of old-fashioned glimpses of evil in the dark.

Though props are down to Jennifer Spence’s eerie production design, with the sets recalling Bram Stoker’s Dracula. If only Hardy and writer Gary Dauberman – with story input from Wan – went with the high camp of that movie.

For all its disappointment, it’s unlikely The Nun will be the last we see of this bad habit as long as those staggering numbers remain undead.