Starling House by Alix E. Harrow

Opal is a lot of things - orphan, high school dropout, full-time cynic, and part-time cashier - but above all, she’s determined to find a better life for her younger brother, Jasper. One that gets them out of Eden, Kentucky, a town remarkable for only two things: bad luck and E. Starling, the reclusive nineteenth-century author of The Underland, who disappeared over a hundred years ago.