The good news is that "Knife Edge" marks the horror genre return of Anthony Hickox. The bad news is that it sucks.
Returning to England, Wall Street trader Emma (Natalie Press) has married Henri (Matthieu Boujenah), and the two and their son move to a large mansion. This being a horror movie, it turns out that the mansion has a dark history, and Emma soon starts seeing visions of murder and hearing menacing voices in the halls. But is she really seeing this (she is) or is she going crazy? Why is their son acting so weird? Why should you care about any of this.
If I could describe "Knife Edge", it would be "Very boring and poorly put together." Sure, it's got plenty of atmosphere and a suspenseful score, but none of the movie is suspenseful or scary. It all thing plays out more like an R-rated Lifetime movie than it does an effective haunted house yarn. Here, every cliche (murderous ghosts, blood filled bathtubs, the caretaker who knows too much, etc.) are all touched, and not surprises are available. The acting is also poor, with Boujenah in particular coming off as wooden and unnatural in his delivery. Add to some lame plot twists, uninteresting characters and an ending that feels rushed, and you have something that's wastes your time more than it is a time waster.
The biggest sin however, is how badly directed the whole thing is. Watching this, it's hard to believe that this is from the man that gave the world movies like "Sundown: The Vampires in Retreat", "Waxwork" and it's sequel. This has none of the energy and fun of those movies, and instead feels like it was made by an inexperienced first time director instead of someone who delivered entertaining genre movies. I can understand Hickox wanting to do something a little more serious, but he comes off as out of his league here, unable to do anything interesting with the material and confused as to what to do with it.
If you want to see a good Anthony Hickox movie, then go watch "Waxwork" or something. If you want a good British haunted house movie, then watch "The Innocents" or "The Legend of Hell House" instead of this.