Set in the same continuity as A Kingdom Divided, about nine years before its events.

Badlands. The deserted land, home of changelings and many more, even worse creatures. Ponies rarely wander there, except of a small group of volunteers, protecting Equestria from incoming changeling swarms. For long, their job was enough to accomplish that. But now, they have to go to the very heart of the infestation.

The Nest.