Pilgrim's Progress is a rare and valuable book.
The Griffin Rock Mayor Luskey Library had a copy of Pilgrim's Progress. Frankie Greene had it checked out, but lent it to Cody Burns who in turn let Boulder read it. Also interested in the book was Skip Scobble, manager and stunt double for Maven Danger, who manufactured an excuse to travel to Griffin Rock so he could attempt to steal it. After breaking into the library and laboratory, he tracked the book down in the fire house, only to be promptly caught by the Rescue Bots.