How far would you go to get rid of an annoying brother? Twelve-year-old Athene Enright is delighted to encounter the mysterious and magical Humble Gloam tribe one moonlit night. And when she is offered an ingenious chance to get rid of her irritating younger brother, she jumps at it. It's not long before Athene begins to miss her brother, and realises she must venture into the underground world where he is imprisoned - deep beneath the roots of a gnarled oak tree. And so begins a journey into an incredible world of dark magic, underground kingdoms and twisted histories.