Terra Incognita: The Abyss by Joshua Mays ($2.99)
Benjamin Harking is an independent teenager who often comes home from his boarding school to an empty house. During one lonely Christmas vacation, he finds a hidden room, secreted away beneath the stairwell. Inside is an ancient book that opens a doorway into a dark world of myth and magic. Forced on a quest for four magical items, Ben will face danger at every turn, meet new allies, and do whatever it takes to complete his goals before the evil Azothothus has a chance to exact his plans -the awakening of the primeval beings known only as the Hollow.