What happens when Satan decides to invade Mexico's ancient deities?

This takes place during World War II, so its savageness is hidden by the political war raging across the globe. Bruce Sherman and a small band of United States Marines are thrown into the clash with Satan's evils.

Not only are they fighting evils in Mexico but they are also contesting Mexico City, Washington's indifference, and Aztec deities who refuse to fight the forces trying to dominate their domains. Bruce's own men often refuse to believe what they are fighting.