It’s a common pitfall when adapting short stories to film: there often isn't sufficient material to sustain a full-length movie. This is definitely what happened here. The narrative centers on two scientists, "Tillinghast" (Jeffrey Combs) and "Pretorius" (Ted Sorel), who have created the "Resonator," a machine that enables individuals to perceive reality in a three-dimensional way, revealing a dimension normally hidden from view. However, this glimpse into our world has attracted some very nasty creatures, eager for a visit. Naturally, there's some violence as a result, and soon “Tillinghast” and psychiatrist "McMichaels" (Barbara Crampton) are searching for a means to confine and send their monstrous guest back to his own plane of existence before the number of casualties increases. The special effects employed are quite good—and for roughly thirty minutes, the story itself holds up well. There has to be more to the universe than what we can see with our eyes, or so it seems. Unfortunately, the subsequent thirty minutes feel thin and the narrative never regains its momentum leading up to a fairly well-constructed ending that is genuinely amusing, though somewhat short on suspense or threat. The performances aren't notably better than you might find in an average episode of "Starsky & Hutch," but that’s not really the focus. It’s the inventive visuals that succeed here. They aren't particularly frightening, but they are imaginatively designed with a minimal reliance on fake blood and bubbles. Not exactly a masterpiece, but it provides enough enjoyment to be worthwhile.

Source on TMDB