The bio-hazard

This story is a concept for another novel I'm working on, I'm posting it as a means to get reviews on the concept so I can apply it to the main story. what if the world was invaded by supernatural beings from another dimension, some of these beings resembling creatures from myths and legends across the world, what if these beings brought an end to life as we know it? follow the story of Morgan, a child born in this world of myths and monsters.