Devlin Macky makes a grave error when purchasing a copy of The Necronomicon. Unwittingly, he opens the First Gate, unleashing a horde of monsters throughout the city.
Macky and Millie must try to put the city back together before the Thirteenth and final gate opens.
But Yog-Sothoth, the Lurker at the Threshold, is poised to enter from the Outer Darkness, fulfilling a desire he's had for over a millennium: the eradication of the human race.