A pony air-sailor and her crew find themselves in the human lands during a relief mission, to research and perhaps cure a plague has caused so much suffering among the lower classes. However, the nobility of this kingdom, fearing the spread of this disease, have enacted extremely harsh measures and curfews, raising tensions. Eventually, the king's adopted brother, furious at the treatment of the common folk, leads a rebellion. the ponies are caught in the fighting, their ship rendered unable to fly when a siege engine misfired, the doctors aboard torn between their duty to heal and the princesses missive to escape. The princess herself is forced to send soldiers to retrieve the stranded teams. as the violence intensifies, the ponies must survive and keep as many people safe as they dare, especially when harboring wounded from either side might be a death sentence

Hmmm... interesting

You are getting good at coming up with story ideas.