Spending some time at a remote cabin in the woods, Hal and his fellow shapeshifters attempt to pass the time with the Box of Fables, a magical trunk that brings fairy tales to life in the worst possible way. Then it's off to an icy mountain on a harmless mission to investigate the legendary Lair of Bigfoot, where they become embroiled in a feud with the neighboring cryptids on Yeti Mountain. This leads to a terrifying discovery: Hundreds of eggs have hatched, and angry lava-breathing dragons are bent on the extinction of humans. This is the most dangerous mission yet for Hal and his friends as they seek to end the Siege of Dragons across the land.