Fablehaven (Book 4): Secrets of the Dragon Sanctuary, Brandon Mull
Two hidden artifacts have been found. More preserves face destruction as the Society of the Evening Star relentlessly pursues new talismans. Desperate to stop them, Kendra discovers the location of the key to a vault housing one of the artifacts in Patton’s Journal of Secrets. In order to retrieve this key, the Knights of the Dawn must enter a death trap - a dragon sanctuary called Wyrmroost. Will anyone who enters the sanctuary make it out alive? Or have Kendra and Seth finally gotten in too deep?