In the final installment of Adam-Troy Castro's creepy Gustav Gloom series, the fate of the Dark Country rests on Gustav and Fernie's shoulders. After weeks of traveling on a quest to find their fathers, Fernie and Gustav finally come face-to-face with their nemesis—the evil Lord Obsidian. Filled with heroic action sequences, terrifying chills, and plenty of humor, this final book will keep fans on the edge of their seats.