A very special day for Petrie approaches- the day he will prove himself able to fly with the adults.
However, he has a problem flying with his siblings, making them mad at him.
When a stranger unlike anything anyone saw before comes to the valley, Petrie and his friends help him find out what he is, and on the way Petrie learns what he needs to do to fit in with the herd.
Meanwhile, Cera needs to cope with having a new baby sister.
