The Ten Thousand Doors of January by Alix E. Harrow

This debut is for you if you reread the Narnia books, lived for the idea of a doorway to a hidden world appearing as you wandered alone in the forest and love a good gothic mystery. In the early 1900s, January's father fails to come home from one of his treasure-seeking trips for his employer, Mr. Locke and so January becomes the guardian of Mr. Locke and lives in his grand manor home. She is not white, she never really feels like she is family and with the exception of Samuel and her dog Bad, she is lonely. As a magical book falls into her hands and she discovers her parent's history and her own, January will come to the attention of some sinister people who wish to possess her. The doors she opens into many magical places lead to fantastic new worlds that so far have only existed in people's imaginations. The sinister characters, as well as the feisty heroine and friends, will worm their way into your heart.