Fluttershy had gone off to Cloudsdale for several days. No warning, no 'goodbye, be back soon', nothing. All they know is that she received a letter from who knows who to meet somepony and is off to Cloudsdale. That was almost two week's ago. And since she's gotten back she has kept herself locked in her home, refusing to see or speak with anyone. Why? Her friends don't have the slightest clue. They also don't know that the reason will lead them to more darkness and strife than they know.

On her latest administrative mission, Princess Twilight Sparkle and her entourage of friends are off to the frozen north-western reaches of Equestria.
There, in the icy cold over three centuries before, Princess Celestia established a small colony as a base for the future settlement of the region. The purpose was to spread the ever increasing numbers of citizens out over a wider area and avoid over-population. It is a similar idea to Appleloosa's and even Ponyville's founding.
The difference though is that this colony, Koltsovo as it's known, was Equestria's first and most dreaded penal colony. Though there are few such colonies of Equestrian criminals, this one has been the bane of Celestia for her to allow admittance, seeming resistant to being admitted into the kingdom. Now this developed, populous and, as they call it, 'industrial' land may at long last be ready.