This is a slasher that plays it by the rules, so if I'm spoiling anything for you, it's because you've never seen a slasher movie before.
Prom Night IV gives us the gift of slashing in a film that is lit with decent effectiveness, not shot notably poorly, with sub-par to decent acting and some moderately suspenseful scenes. The prom thing is more or less done in the intro, where we get to see a couple slashed in a prom in 1957. Our mad killer here is a Catholic priest gone horribly wrong--he kills with a cross where the long end has a blade.
Our victims, two teenaged couples, are headed down to a retreat that used to be an old monastery for a weekend of debauchery. Meanwhile, a young priest newly charged with watching over the insane priest (who's been kept underground by the Church) is developed for a bit, but manages to slip in his duties. (Prom Night IV is very good at giving "bonus slashes" before it gets around to killing the teenagers.)
The highlight of Prom Night IV is Nicole de Boer, who you might remember from The Cube or Star Trek: Deep Space Nine (she was Ezri Dax). Her acting, which is pretty good, manages to elevate the rest of the movie (since she is the film's heroine). The rest of the cast is pretty small-time, though, and doesn't live up to Nicole.
It does have the requisite T&A shots (and a really poor sex scene), to be certain, and it manages to fit 8 deaths into a film that only focuses on those 4 teens. All are pretty freaky and well done, too. Once the suspense starts, it's pretty good at not letting up, despite following the rules strongly. The extended scenes before the slasher starts on the teens build everything up quite well.
This is a slasher movie, and you will enjoy it only if you're in the mood for one. However, it does what it does well, and as such is worth picking up if you are.
