The Children of the Lost — David Whitley

At the end of The Midnight Charter, Mark and Lily had been cast out of the city of Agora. Now, they must survive in a dense forest filled with strange villages, terrifying nightmares, and powerful witches. It's even more frightening than the slums and secrets of Agora. In an adventure that expands with every turn of the page, David Whitley delivers a novel as thrilling and horrifying as his characters' darkest dreams.