The Atrocity Archives (Electronic book text, Ace trade pbk. e.)

In the title piece, Alan Turing, the father of modern computer science, completes his theorem on "Phase Conjugate Grammars for Extra-dimensional Summoning." Turing's work paves the way for esoteric mathematical computations that, when carried out, have side effects that leak through a channel underlying the structure of the Cosmos. Out there in the multiverse are "listeners" who can sometimes be coerced into opening gates. In 1945, Nazi Germany's Ahnenerbe-SS, in an attempt to escape the Allied onslaught, performs just such a summoning on the souls of more than six million. A gate opens to an alternate universe through which the SS move people and material-to live to fight another day. But their summoning brings forth more than the SS have bargained for-an evil, patiently waiting all this time while learning the ways of humans, now poises to lunch on Earth. Secret intelligence agencies, esoteric theorems, Lovecraftian horrors, Middle East terrorist connections, a damsel in distress, and a final battle on the surface of a dying planet round out this story.