Changelings are one of the most mysterious races known to Equestria, and one of the most divisive subjects in Equestria today. There have been apologists and partisans for them, and groups of ponies who wouldn't trust one as far as they could buck them. There are myths and legends, rumours and anecdotes, that paint contradicting pictures of them as loving pacifists and bloodthirsty monsters; as beneficial tutors and wise sages, emotion-eating vampires and mind controllers; as possessors of hive minds, ruled by numerous Queens, of being a young race that has only ever acknowledged Chrysalis as ruler; and of rouges that forsook their own to live among ponykind, and infiltrators who treacherously betrayed those that had grown to trust them.

Twilight Sparkle, in light of disquieting rumors of an imminent second Changeling invasion and a spy on the loose in the Crystal Empire, decides to disseminate all she knows about Changelings to the general public.

Some of that knowledge may prove to be critical in the days ahead.