The Killing Hour is one of those movies that's full of potential, but never quite reaches it. The one thing you should know rather quickly is the killer is a character already in the movie and not someone who pops up at the end. You should figure out quickly who it actually is, but there a few scenes that might make you 2nd guess that. But it's not really a surprise, on who the killer is, but their motive is the twist that while is fairly interesting, one would think the police would figure it out. It's one of those twists you have to watch what you say or the whole movie will be spoiled and while again the twist is fairly good, but not sure how the cops wouldn't figure it out.
The screenplay by Jonathon Ringkamp was the biggest problem with the movie, while not poorly written it's just that the characters lack any depth and really aren't all that interesting. The concept was quite interesting, but the screenplay is the downfall here. Again it's not poorly written, but the characters just aren't interesting, which wouldn't be so bad had the movie focus on the murders. Since its more character driven well you need solid characters something this doesn't have.
Director Armand Mastroianni made his directorial debut with the slasher flick He Knows You're Alone, which was actually the very first film Tom Hanks appeared in; Mastroianni really isn't a bad director, while he's not great or anything he can deliver a well-made movie on a limited budget and while I'm no expert on his career he's done some enjoyable movies. He Knows You're Alone was a solid if not clichéd slasher flick that was actually shot in Staten Island, Ny where I live and I've actually hung around in the areas it was shot so maybe I'm a bit biased.
With the Killing Hour he doesn't make as fun as a movie as his debut, but the problems here are with the writing and not the directing. Mastroianni gets the best out of each scene, but there really wasn't much he could do to make up for the shortcomings of the script. As I stated earlier you should figure out who the killer is rather early, but Mastroianni is able to add some nice touches to make you 2nd guess that.
The cast is pretty good with Perry King and Norman Parker give solid performances despite not having the best of material. Elizabeth Kemp as Virna Nightbourne is the strongest character, but is given little to do in the first half and by the time she enters the movie most of the potential is now gone, but Kemp makes the best out of a weak character.
Overall The Killing Hour is by no means a bad movie, but never reaches the potential it had. The twist is interesting, but cannot save the movie. In the end it's an alright movie; you could do better, but you can also do a lot worse.