Ombria in Shadow by Patricia A McKillip ISBN 13: 9780441010165

When Ombria’s prince, Royce Greve, breathes his last—in palace rooms high above the city—he leaves his young son and mistress at the mercy of his ancient and powerful great-aunt, Domina Pearl. Meanwhile, in a dreamlike underworld peopled by Ombria’s ghosts, a sorceress weaves her spells and brews her potions, never revealing her real face—or true heart. And somewhere in between, the struggle to rule the whole of Ombria—both its light and shadows—will rest in the hands of those whose fractured lives align like the lost pieces of a magical puzzle….