The Dark Days by PM Griffin
As it becomes ever more evident that the long-promised divine chastisement is close at hand, Helena Moriarty, her associate Doctor Leonard Duck, and her family hasten to make what preparations they can and to warn others in the community around them. Disbelief is strong even among their own kin, and when the disaster strikes, all too many are unready to meet it.
The people and their animal charges brace themselves to endure and to survive as total darkness and bitter cold envelop the world. Fiery bolts sear downward, and walls of flame sweep through the streets, but these pale into insignificance as Hell’s demons are released to take whatever humans they can claim or slay those who refuse submission. These infernal entities cannot be fought by mere human strength or weapons, yet Helena must fight, or she will fail the two small creatures she is pledged to defend.