Deep within the Everfree lives a civilization of creatures long thought to have disappeared without a trace. How will Equestria handle a blast from a very distant past.

The Cutie Mark Crusaders need to stop an ancient pony demon they released from a museum vase, before it's too late.

A culture long since hidden from pony-kind gets rediscovered, when a foal gets to close to the forest edge. What will happen when an ancient culture collides with one far more advanced?