We endured this turkey in its entirety last night after watching "Destination Moon" (1950), so we were certainly in the right frame of mind for a good dose of hokey 1950's "B" sci-fi.
This is a disappointingly dull and uninteresting pot-boiler, obviously intended for no other purpose than being run as a second feature.
I am baffled by the reviews here claiming that this is "ahead of its time" and comparing it with old "Outer Limits" or "Twilight Zone". I have to wonder if I was really watching the same movie.
The acting could have been done as well by wooden cigar-store Indians. The dialog (for the most part) is insipid. The only "special effects" are a shaky and out-of-focus camera on a few shots.
While the director had a great location to work on - a massive old mansion - he failed miserably in using it to his best advantage. He could have used the setting to really ramp up the tension (as was done with "Saltair" in "Carnival of Souls") but instead about half of the movie is shots of the two main characters wandering around and back and forth, seemingly lost on a large estate.
When the best things about a movie are the cars (a 1954 MG TF, a 1962 Plymouth Fury Wagon, and a 1960 Plymouth Taxi Special), and it's NOT a movie about cars, you know it's a loser.