It follows a "What If" scenario where the follow-up expedition in Lovecraft's "At the Mountains of Madness" has occurred, and inexorably fuses the Cold War and Cthulhu Mythos.

    P. Lovecraft's work knows of the Necronomicon, the black magic grimoire he invented as a literary prop in his classic horror stories. There have been several attempts at creating this text, yet none stand up to Lovecraft's own descriptions of the Necronomicon...until now. Fans of Lovecraftian magic and occult fiction will delight in Donald Tyson's Necronomicon, based purely within Lovecraft's own fictional universe, the Cthulhu Mythos.This grimoire traces the wanderings of Abdul Alhazred, a necromancer of Yemen, on his search for arcane wisdom and magic. Alhazred's magical adventures lead him to the Arabian desert, the lost city of Irem, ruins of Babylon, lands of the Old Ones, and Damascus, where he encounters a variety of strange creatures and accrues necromantic secrets.

    Delta Green weaves the comic terrors of the Cthulhu Mythos seamlessly with the paranoia and shadowy forces of conspiracy theory, updating the stories of jazz era horror writer H. P. Lovecraft to the modern day.