From publisher blurb:
The Cthulhu Mythos is an excellent backdrop for any Fate Core campaign. This book includes a present day Cthulhu setting and a compact version of the Fate Core rules, so you have everything you need to confront cosmic horrors in one place.
This 136-page book provides Mythos locations, Monsters, NPCs, the Dreamlands, an example scenario, several cults, a secret history of the Earth, and uncanny Mythos tomes, with the spells and powers they contain.
The Earth is doomed and there is nothing your puny efforts can do to avert its fate, but it's your duty to try!