Traveling to return to the present day, the three Norns run low on magic and are forced to stop and rest at a random point in space and time. Takes place during the trip home in the Flights of Fancy episode "Ah! The Goddess's Confession", and in the anime continuity of Black Butler, some time in the latter half of the first series. Minimal spoilers.

After the Elements of Harmony defeated Discord and returned him to his stone prison, Celestia decided that having him anywhere near Equestria was unacceptable. Chaos, however, is extremely unpredictable, and tends to seek out its own...