When Martin’s great-aunt brings him an unusual pair of shoes, Martin is determined to find the strange marketplace where she bought them—the Black Market, a constantly relocating swap meet where the world’s strangest and most dangerous items are exchanged by some very suspicious (and disguised) characters. Though his aunt has sworn him to secrecy, he enlists the help of his best friend Jess to find the Black Market on Halloween. Soon, Martin trades his shoes for the legendary Bag of Dirty ...