The first-person narrative concerns a man from the ancient city of Carcosa who awakens from a sickness-induced sleep to find himself lost in an unfamiliar wilderness.
A man from the city of Carcosa, contemplating the words of the philosopher Hali concerning the nature of death, wanders through an unfamiliar wilderness. He does not know how he came there, but recalls that he was sick in bed. He worries that he has wandered out of doors in a state of insensibility. The man calms himself as he surveys his surroundings. He is aware that it is cold, though he does not exactly feel cold. He follows an ancient paved road, and sees the disassembled remnants of tombstones and tombs. He comes across a lynx, an owl, and a strange man dressed in animal skins carrying a torch, who ignores the narrator. For the first time, the man becomes aware that it must be night, though he can see as clear as day. The man sits near a tree whose roots emerge from a grave. Looking at the stone that once marked the grave, he sees his name, the date of his birth, and the date of his death. He then realizes that he is dead, and is amid the ruins of the "ancient and famous city of Carcosa."
A footnote at the end of the story states: "Such are the facts imparted to the medium Bayrolles[3] by the spirit Hoseib Alar Robardin."
Carcosa was subsequently borrowed by Robert W. Chambers as the setting of his fictional play, The King in Yellow, and features heavily in many of the stories in the book of the same name.
Alluding to The King in Yellow, Carcosa was mentioned in the first season of the TV series True Detective.