The Vampire Bat (1933)

This is clearly a Poverty Row picture in a lot of ways, and it's not just the limited number of locations. Filmed at night on Universal's European village set, the interior of Lionel Atwill's house is from The Old Dark House and nothing much really happens to advance the main plot. A large chunk of the movie is taken up with hunting down Karl, and the doctor's plan is not explained in a very comprehensible way. His discovery comes not as the result of Melvyn's investigation, but more by chance. Still, this is far better than some of the films I present. The movie is moody and atmospheric, and it works hard to give everything a rational underpinning, plus it gives you an excuse to stare at Fay Wray for an hour or so, which can't be a bad thing.