Where is Princess Luna??

Celestia begins wondering where in equestria Her sister is when nopony has heard from her in three days, obviously hilarity ensues!

Disclaimer, this is my first non spider-man story.

Luna has not been seen for three days, so Celestia, after the usual meeting, goes to investigate, Will she find the Princess of the moon? Will she find Equestria's resident human? Will she finally get the cake?!