In the mountains surrounding Equestria lies several Changeling hives. One of the hives, known as Wraith attacks the neighboring hive of Hypos, leaving only two known survivors, Mimic and Thraxus.
Mimic, the only heir alive to Hypos, as far as anybody knows, and Thraxus, a royal guard of Hypos, then find themselves on a quest to find any living survivors from the attack, rebuild Hypos, and get revenge against Wraith for destroying their home.