The story follows Walter Gilman, who takes a room in the Witch House, an accursed house in Akham, Lovecraft's fictional New England town. The house once harbored Keziah Mason, an witch who disappeared mysteriously from a Salem jail in 1692. Gilman discovers that over the centuries most of its occupants have died prematurely. In his dreams while at the house, Gilman travels to the city of Elder Things and communes with the evil witch and her henchmen.
Barzai the Wise, a high priest and prophet greatly learned in the lore of the "gods of earth", or Great Ones, attempts to scale the mountain of Hatheg-Kla in order to look upon their faces, accompanied by his young disciple Atal. Upon reaching the peak, Barzai at first seems overjoyed until he finds that the "gods of the earth" are not there alone, but rather are overseen by the "other gods, the gods of the outer hells that guard the feeble gods of earth!" Atal flees and Barzai is never seen again.
Thomas Olney, a "philosopher" visiting the town of Kingsport, Massachusetts with his family, is intrigued by a strange house on a cliff overlooking the ocean. It is unaccountably high and old and the locals have a generations-long dread of the place which no one is known to have visited. With great difficulty, Olney climbs the crag, approaches the house, and meets the mysterious man who lives there. The only door opens directly onto a sheer cliff, giving access only to mist and "the abyss". The transmittal of archaic lore and a life-altering encounter with the supernatural ensue, as Olney is not the only visitor that day. He returns to Kingsport the next day, but seems to have left his spirit behind in the strange, remote dwelling.