Sky Raiders (Five Kingdoms 1) – Mull Brandon

Adventure awaits in the Five Kingdoms – come and claim it in this start to a new series from the number-one New York Times best-selling author of the Fablehaven and Beyonders series.
Cole Randolph was just trying to have a fun time with his friends on Halloween (and maybe get to know Jenna Hunt a little better). But when a spooky haunted house turns out to be a portal to something much creepier, Cole finds himself on an adventure on a whole different level.