Petrie is having a difficult time preparing for "the day of the flyers" and important day for all of the flying residents of the Great Valley, when all of the young flyers must participate in a very precise flying exhibition to prove that they are ready to fly with the adults. Always a nervous flyer, Petrie has even more trouble flying with his sibling in precise group formationshe's more of an independent, free-style kind of guy. At the same time, a strange newcomer to the Great Valley has Littlefoot and his friends trying to help figure out just exactly what he is. Named Guido, he's the strangest looking creature any of the Great Valley creatures has ever seen, especially since he's covered with multicolored "fuzzies" (feathers!), and has never seen another like himself. Cera is having her own troubles, as her grumpy Dad and his new mate, Tria, get ready to welcome a hatchling to the family. All of these issues come together on the night before "the Day of the Flyers", when Guido starts to figure out what he is, inadvertently leading all of the gang on a perilous adventure into the Mysterious Beyond.