Eden's Everdark / Karen Strong.

Enhanced descriptions from Syndetics:

Hailed by Newbery winner Kelly Barnhill as "stunning, moving, and marvelously strange," this tale of a young girl who stumbles into a magical realm ruled by a wicked witch is a haunting and ultimately uplifting middle grade novel about grief, family, and decades-old magic.

Still grieving the loss of her mother, Eden visits Safina Island, her ancestral home, as a healing balm. But when she discovers an old sketchbook that belonged to her mother, she's haunted by the images she sees drawn there. A creepy mansion covered with roots and leaves. A monstrous dog with dagger-sharp teeth. And a tall woman with wind-blown hair and long, sharp nails who is as beautiful as she is terrifying.

Days later, exploring the island alone, Eden follows a black cat through a rift in the bright day. She stumbles into Everdark, a parallel world where the sun never rises, where spirits linger between death and the afterlife, and where everything from her mother's drawings is all too real--especially the Witch of Everdark, who wants to make Eden her eternal daughter.

Can Eden find a way to defeat the witch's magic? Or will she remain trapped in Everdark forever?