From the publisher:
This 128 page book unlocks a world of pain for your Investigators. Giant terrors, vast Nazi war machines, Mythos creatures and Elder Gods re-imagined in the Achtung! Cthulhu universe with stunning colour & B&W art. You'll also find regional Mythos gargantuan's to go with the regional Guides. Not just a monstrous compendium - Terrors of the Secret War will provide plots to introduce each of the Terror's and new rules to allow your Investigator's to try to take on these ancient or epic scale foes!