Billy's family is moving to another town, but when the question arises of whether or not Grim goes with Billy, Billy and Mandy decide to settle this in the courthouse!
Jack, a headless prankster from Grim's past, uses Billy to steal Grim's scythe so he can destroy Grim and take over the world with demons from the Netherworld.
When Irwin turns into a werewolf, Billy enters him in the dog show. Mandy visits the old haunted house down the street, which nobody has emerged from in years. Will Mandy make it out alive?
In "Nergal's Pizza", Nergal and Grim start rival pizza franchises. In "Hey, Water You Doing?", a trip to a water park goes south when Billy, Mandy and Grim all wind up underwater and a mermaid falls in love with Billy.
In "El día de los muertos estupidos" the gang travels to Mexico where Billy finds his long lost twin brother. In "Heartburn" Billy and Mandy use Grim's camera that reveals true heart, and discover a disturbing truth about Irwin.
In "Spidermandy" Mandy contracts spider-pox from Jeff the spider and becomes a spider herself. In "Be A-Fred, Be Very A-Fred" Grim must spend a day with Fred Fredburger, but that turns out to be a horrible experience for all.