It's Day 3 of 12 Authors of Christmas!
Land of No Angels
The Ascension marked a demon apocalypse that decimated the human race and forced survivors into hiding. Sixteen year old Rebecca Ashford and her younger sister, Errol, have spent the last year hidden in their family's tornado bunker. When the sound of a screaming baby wakes them in the middle of the night, they attempt to save the infant and Errol is poisoned by a demon.
With only a week until the poison consumes her, Rebecca must trust a mysterious survivor named Fox to help her find a cure. Together, they confront demons and other monsters while Rebecca struggles to learn magic that will help them locate the ingredients needed to save her sister.