With most haunted house movies, only the first half is scary. Why? Because all of the ghostly activity is completely unexplained in the first half. There are banging noises and creepy whispers and flickering lights and bass-voiced toddlers, and nobody knows what the hell is going on. But then the second half rolls around, and of course the ghost needs a back story, and the ghost’s death needs to be avenged, and before you know it the ghost is reduced to a nagging spiritual presence, needing all this random shit done like your wife on Saturday morning, and the whole movie just stops being frightening. With few exceptions, the modern haunted house movie serves the ghost rather than the audience.

Knife Edge, a recent DVD release from the U.K., pours a little too neatly into that oh-so-common haunted house movie mold. With his business flourishing, Frenchman Henri spontaneously moves his new wife and young stepson from New York out to a bulging mansion just outside of London. He secretly purchased the mansion several years before, after the previous tenants suddenly abandoned it. While Henri occupied with his flourishing business, his wife Emma is frequently left at home alone with her young son. It doesn’t take long for her to begin to suspect that the spacious mansion might be haunted.

At first the paranormal signs are relatively benign. Some quiet whispers in the hallways. The faraway sound of a child crying out for its mother. Images of bloody violence flashing behind Emma in the bathroom mirror. She might be going crazy. Or maybe not. Maybe it’s all real. It’s certainly hard to tell when you’re watching a movie that’s this downright manipulative.

Like most successful haunted house movies, Knife Edge is unabashedly frightening during its first half. The early scares are genuine, with eerie sounds and bloody images that really work their way under your skin. Staged with an impressive finesse by veteran horror director Anthony Hickox (Hellraiser II: Hell on Earth), these inspired first-reel scenes are convincing enough to compel you to watch the film all the way to the end. Too bad the movie as a whole is so overloaded with perfunctory haunted house subplots—Emma has a miscarriage, a mysterious nanny (Joan Plowright) appears on the scene to dispatch dubious advice, the young son forges an imaginary friendship with an ugly doll—that the later plot twists bear little impact. The audience is left with a brilliantly directed haunted house movie that’s crippled by a messy, convoluted mystery-movie narrative.