The story has a scoop-seeking anthropologist Joe Weber (Cohen regular Michael Moriarty in another pleasing turn) going off with his problem son whom he has not seen in years to an inherited house in a quiet ancestral town where they can sort their issues...and yes, that place is Salem's Lot. In Cohen's version, the town has been entirely taken over by vampires, who constitute a society unto themselves, using humans only as servants. They are intrigued by the anthropologist and want him to write a chronicle, nay bible, of vampire civilization. In turn Joe's son is intrigued by the vampires and not sure if he doesn't want to become one himself. Cohen's pacy script presents his quirky and subtly humorous take on a vampire society with its peculiar lifestyle and its own attitudes towards the human race. He also presents the gripping dilemma that Joe faces, forced to stay and write for his son's safety and at the same time seduced by the prospect of writing a unique chronicle...and by an ex-girlfriend who has never aged after he left.
Thus far is a film that's plainly brilliant in its setup and I would have loved to see a greater progression in this vein. But after that Larry's script seems to have run out of ideas or time and he quickly reverts to a showdown where Joe teams up with a crusty old vampire slayer (played by maverick movie-maker Sam Fuller, and there's also a cheeky reference to his film Pickup on South Street) who just happens to have blown into the town. There occurs that same abrupt change of tone that happened in John Carpenter's They Live which, beginning as this quietly unsettling SF thriller, suddenly veered off into high camp territory with the scene where Roddy Piper decides it's time to 'kick ass and chew bubblegum'. To it's credit, RTSL goes for much longer before the camping grounds are laid, and even after that, retains a good modicum of interest.
Thus while not entirely streamlined or satisfying, RTSL is a film with several points of interest and IMO one that deserves a better appreciation than it has thus far received.