After the chaotic debacle in the Crystal Empire, and a week's respite, Twilight secrets Sombra away to his new home in the Everfree Forest. The Castle of the Two Sisters is vacant, decrepit, dark. It's the perfect place to hide the former tyrant.

While she plans to continue her tutelage under her new friend, however, a metaphorical wrench is thrown into said plans when Ponyville makes a new and sudden addition to its town guard.