Bone & Ember Book 1. The Burning World Series, #1

The fire in the hollow mountain went out three hundred years ago. What crawled out after has been hungry ever since. Mara Ashvane speaks to the dead. It's not a gift - it's a debt, and it's been collecting interest her whole life. When a drained corpse turns up at the edge of the Ashfeld Plains and the gray begins to spread, she knows something older than grief is moving through the world. Calder Voss investigates boundary violations for the Church.
He's seen strange things. He hasn't seen anything like this. Together with a child who draws maps of places she's never been, they follow the cold toward its source. The fire needs tending. The question is whether anyone is left who knows how. Bone & Ember is Book One of The Burning World Series.