While filly sitting the Cutie Mark Crusaders, Rainbow Dash accidently challenges the young ponies to prove their bravery by venturing deep into the Everfree Forest. Little do they know that beyond the muck and mist, lays an ancient portal that connects the human realm to the land of Equestria, and soon, Thomas and Mike find themselves in a war between the humans and ponies, in a battle for peace and a battle for domination.