I've only read a few HPL pieces but this one is the creepiest so far! The story is about a house which, though not haunted is plagued by a strange events caused by some presence. Most of the original family that lived there, the Harris family, died one by one under strange circumstances until it was decided not to rent the house any further. Then, years later, our narrator takes up the case and begins to investigate this shunned dwelling, unearthing the secrets therein and finally deciding to do something about it. The first chapter read like an Introduction to the story; on the edition I read there was no Chapter 1, so when the 'Introduction' ends, which mentions a discourse with Edgar Alan Poe on the said house, I come to Chapter 2 and realise my mistake!
So it seems that the story is going to read like a documentary and in some ways it does (there is virtually no dialogue), but even so it is a creepy tale, one I can definitely recommend as an introduction to Lovecraft's work.