Twilight Sparkle, Princess Celestia's pupil, discovers that Nightmare Moon is set to return "on the longest day of the thousandth year", which is in two days' time. She sends a letter to Princess Celestia warning her of Nightmare Moon's return, but the Princess tells her to "stop reading those dusty old books" and sends her to Ponyville to see to the Summer Sun Celebration preparations and to "make some friends". Twilight Sparkle does as she is told and inadvertently befriends five ponies, but is still confused about the Princess's insistence on friendship.