The Resurrected (1991), which is The Case of Charles Dexter Ward set in the late 1980s and from the PoV of the detective hired by Ward's wife to investigate her husband's disappearance following a mysterious change in personality.

That sounds like it could be great, so long as it didn't fall prey to the Dracula problem (Characters: "What is this mysterious malign force that has suddenly entered our lives?" Audience: "VAMPIRES YOU MORONS DIDN'T YOU READ THE BOOK?"). How does it work?