The Frozen North. The Crystal Empire. Both were names for the arctic land north of Equestria. During the Final War, the Empire had tried to help Equestria in the beginning. Then, as it escalated, the Empire withdrew it's support, instead favoring isolationism. When the balefire bombs finally dropped, the Empire did not go by unaffected. As the fallout turned the once beautiful snow into a death trap, the citizens had scrambled to try to build some form of safety.
The result were massive, dome shaped structures called Habs. These Habs housed entire towns of ponies and are located in the old world ruins of said towns. They are sealed from the outside world in an effort to keep the radiation out. It isn't foolproof, however. Leaks occur and ponies die before it's plugged. The simple need to wear full radiation suits and gas masks to just travel outside has led to some isolation between Habs. Life is hard in the North.
Snowbank and Snow Angel, brother and sister respectively, are two crystal ponies from the Dreaded Snow Hab. Sent with a message for another Hab near the ruins of the Crystal City, the siblings will be faced with the hardships that the arctic wasteland has to offer. Can they get the message to the Hab and get home or will the Wasted North have a different plan for them?