It's a shame more people didn't see the brilliantly strange Reality last year, in which Sydney Sweeney played Reality Winner, a woman accused of leaking intelligence on the US, itself taken from real transcripts of the interrogation. Off the back of that Sweeney has given us Madame Web and now Immaculate. The latter is also a production of hers and apparently a labour of love.

Sweeney is, naturally, committed to her role as Sister Cecilia, an American nun who moves to a convent for ailing nuns in Rome where she suddenly discovers she's pregnant without having had sex.

Director Michael Mohan does well turning Andrew Lobel's so-so script into a working film, bringing stylish direction to the inner workings of the convent and an eerie sense of foreboding. It's Lobel's lacklustre writing that doesn't do much for the most part, setting up a hokey ‘jump jump' type film that at times hints at a more interesting film beneath it.

It might not be fair to Lobel, as films are messed around in production and writers often get the blame and there is good stuff in there. For all the guff about immaculate conception and scary nuns going “boo”, there is a genuine comment on the corruption within the church. How those in power within religion can excuse their actions because they believe God has given them the right to do so. There are also hints at commenting on how institutions use young people searching for answers to further their causes.

But a lot of this is lost to the jump scares. Sweeney isn't alone in her well-modulated performance, though underused Benedetta Porcaroli is also great as Sister Gwen, a former sex worker and abuse victim who has turned to faith.

Outside of hints and ideas, and a great central turn from Sweeney, there is one huge saving grace. The final five minutes. The final five minutes of Immaculate are ballsy and feel like they're from a different, much more out-there film. Had the film been as audacious and (quiet voices) fun, then this would have been a ride. Instead the final five stand as a frustrating “what if” of a bonkers, nasty film that feels like it could have given Sweeney a real chance to let out her freakiness.

Sadly, the issue with Immaculate is that it is neither second coming nor abomination from the bowels of Lucifer. It's not heavenly, nor is it hellish. It's absolutely okay, and like so many of us, its greatest sin is its wasted potential.

Immaculate is released in UK cinemas on March 22.