The Nyogtha Variations — John Michael Greer

A Whisper from Carcosa...
Five years have passed since Brecken Kendall met the shoggoth she nicknamed Sho and began to discover the unnerving realities hidden behind the stories of iconic weird-fiction writer H.P. Lovecraft. Now Brecken and Sho live in Arkham, Massachusetts, where Brecken juggles the demands of her day job with the early stages of her career as a Baroque composer and musician, and helps Sho stay hidden from the human world and raise six unruly shoggoth broodlings. The mysterious powers and uncanny beings she encountered five years back have faded into the background of her life -- and so has the Radiance, the powerful and secret organization that seeks to exterminate shoggoths and all other eldritch beings in its quest for human supremacy over the entire cosmos.
But strange forces are moving through the narrow streets of witch-haunted Arkham as Brecken is drawn into a tangled web of plot and counterplot in which the stakes are hidden and friend is indistinguishable from foe. At the heart of the conflict is her latest musical project, a Baroque chamber opera based on the brilliant and haunting play The King in Yellow. As the opera moves toward its first performance in Arkham, the Radiance is in motion; so are its enemies, the secretive warriors who serve the Yellow Sign; so is the living darkness the old books call Nyogtha, The Thing That Should Not Be -- and so is the Great Old One Hastur, the King in Yellow himself...