Scott is frustrated as he's missing the most important piece of his jigsaw puzzle of a Scottish castle, the piece which shows the flag flying atop the building. Although the students admit they would rather not hear Mr. Anthony play his bagpipes, Mr. Anthony showing Scott to do a bagpipe breath at least gets Scott not to feel so scrunched up physically, but doesn't relieve his frustration of not being able to find the missing piece. So Mr. Anthony recounts a story of Napkin Man, in taking a kilt-adorned trip to Scotland, to help his friend Fergus find something, namely "Bonnie". The story shows Scott that sticking with the search pays off in a feeling of satisfaction in finding for what he's looking.
—Huggo