It is a continuation of "The Dream-Quest of Unknown Kadath", and was followed by a sequel, "Through the Gates of the Silver Key", co-written with E. Hoffmann Price.

But, still not certain which is truer, he sets out to determine whether the waking ideas of man are superior to his dreams, and in the process, he passes through several unsatisfying philosophical stances.

During one of these dreams, his long-dead grandfather tells him of a silver key in his attic, inscribed with mysterious arabesque symbols, which he finds and takes with him on a visit to his boyhood home in the backwoods of northeastern Massachusetts (the setting for many of Lovecraft's stories), where he enters a mysterious cave that he used to play in.

"[2] "The Silver Key" is thought to have been inspired in part by Lovecraft's visit to Foster, Rhode Island, where his maternal ancestors lived.

[2] Carter's search for meaning through a succession of philosophical and aesthetic approaches may have been inspired by J. K. Huysmans' A rebours (1884), whose main character undertakes a similar progression.