If you want really classic Lovecraft at the top of his form, then this novel is it. It is a good, tight, driven read- except for the extensive prose tour of his beloved old Providence near the beginning. Yet, even this detailed introduction helps to weave an unmatched atmosphere that draws you deeply into Lovecraft's world. This is an ode to Providence, and to those unobtrusive and unlikely heroes that would keep it safe from cosmic evil.
Lovecraft carries us from colonial days to the "modern" 1920's in this tale. We are introduced to the hidden brotherhood of dark magicians and necromancers- those to seek to wield unnatural power from beyond the grave and beyond the stars. So much concentrated occult information, or rather enticing hints of such information, is packed into the narrative. Mystery within mystery unfolds. Yet, it is rather ordinary men that are called upon to confront this inconceivable evil, even though it threatens their very sanity.
Besides being an extremely well written tale of supernatural suspense it also serves as a teaching tale. There is madness out of time and a horror from beyond the spheres that threatens to entrap and destroy the unwary. Do not call up what ye lack the power to put down. Upon this depends more than can be put into words- all civilization, all natural law, perhaps the fate of the solar system and the universe. Perhaps even more than this- all because one fool opened a door and there was no one there with the knowledge to close it...
This is a good introduction into the old-fashioned horror of H.P. Lovecraft.