Arthur has a stomachache after eating too much candy and desserts, and has dreams involving fairy tales made famous by the Brothers Grimm. Arthur and D.W. do not want to spend time with Grandpa Dave because all he does is play checkers and sleep. He tells them about a buried family treasure from their pirate ancestor, so Arthur and D.W. take the map and look for the treasure themselves. However, Grandpa Dave reveals the treasure was just made up as a story to entertain the kids.