When Gustav convinces Fernie's safety-conscious father to enter the Gloom Mansion with Fernie and Perlie to help rescue Gustav's father from the Dark Country, there is a prison break from the Hall of Shadow Criminals, endangering them all.
Fernie What, an adventurous young horror fan, moves into the house across the street from the dark mansion of a mysterious boy whose residence is haunted by evil shadows.
As Fernie and Gustav battle the Shadow Eater, who seeks The Nightmare Vault for his master, the evil Lord Obsidian, Fernie learns about Gustav's mysterious past and just what happened to his missing parents.
