Riverland by Fran Wilde
When things go bad at home, sisters Eleanor and Mike hide in a secret place under Eleanor’s bed, telling monster stories. Often, it seems those stories and their mother’s house magic are all that keep them safe from both busybodies and their dad’s temper. But when their father breaks a family heirloom, a glass witch ball, a river suddenly appears beneath the bed, and Eleanor and Mike fall into a world where dreams are born, nightmares struggle to break into the real world, and secrets have big consequences. Full of both adventure and heart, Riverland is a story about the bond between two sisters and how they must make their own magic to protect each other and save the ones they love.