The turmoil of a foreign land re-opens the rift between the two royal sisters. And drives Luna to seek the reason about her initial betrayal.

Meanwhile, an ancient danger lurking under the sands awakens by the current events. And sets out to fulfill its vengeance.

When pushed to the limit, the nine mercenaries escape to Equestria leaving all their problems behind and starting anew.

With no way back, they must adapt to their new lives and try to fit in into pony society and they must protect them from the unfinished business they left behind.