The Horror 51!?: Dead Men Walk (1943)

In a small town in the West of the USA a burial is held for one Elwyn Clayton. No one, not even his twin Lloyd seems very upset about the man's demise, which in the case of Dr. Lloyd Clayton isn't as strange as one might think. Finally driven to act by Elwyn's satanism and his brother's wish to convert Lloyd's daughter to Gail to the worship of EVIL, Lloyd threw his brother down a cliff. He will soon learn that it wasn't his best idea, since his brother returns from the dead as a vampire and starts a campaign to turn Gail and discredit Lloyd as an insane murderer.
What we have here is...an honest to Cthulhu excellent PRC production with George Zucco doing great, nuanced work as Elwyn & Lloyd. Most of the other actors, Dwight Frye as Elwyn's Renfield excluded, aren't exactly great, but no one is really all that bad, even the young hero (in most movies of this caliber the worst actor on screen) is quite tolerable, perhaps because his role as Gail's fiancé and skeptical counterpart to Zucco's Lloyd keeps him off the center stage for most of the film.
What is great is the script: It transfers a very old interpretation of vampirism that owes more to folklore than to Dracula into the (then) modern day and into a (budget-constrained, but still) palpably un-gothic place. Just as important and noteworthy is an idea that even today isn't used in vampire films all that often: people do not believe in vampires and if you are declaring yourself the fearless vampire hunter they will probably think you're insane. Or even an insane murderer.
Another wonderful point is the surprisingly ambiguous character of our real hero, Lloyd, who started the whole mess by murdering his brother.
Director Sam Newfield deserves some praise, too. He makes the most of the low budget and even provides a very dramatic and effective finale, much more poignant than in most of Dead Men Walk's contemporaries.