The Hastur Cycle by Robert M. Price

A compact collection of interconnected tales and essays that expand on the Hastur/King in Yellow mythos, tracing scholars, cultists, and ordinary people as forbidden texts and rites awaken a diffuse, memetic dread; blending Lovecraftian cosmic horror, occult scholarship, and pastiche, the stories explore how obsession with a haunted city and its pallid prince corrodes sanity, faith, and society.