When Kendra and Seth go to stay at their grandparents' estate, they discover that it is a sanctuary for magical creatures and that a battlebetween good and evil is brewing.

Very strange things are afoot at Fablehaven. Someone or something has released a plague that transforms beings of light into creatures of darkness. Seth discovers the problem early, but as the infectious disease spreads, it becomes clear that the preserve cannot hold out for long.

"As the war with the dragons intensifies, all eyes are turning to Titan Valley for help. A dragon sanctuary unlike any of the others, this one is home to enslaved dragons ruled by the powerful Giant Queen, one of the five monarchs of the magical world. In addition, it houses the arena for the Titan Games, a series of gladiator-style battles presided over by none other than Humbuggle, the demon who stole Seth's memories! Seth is seeking for his memories....