(Based on this fan comic.)

With all the changes ongoing in Maretime Bay, Sprout decides to run away before he can be "brought to justice". But even though he does just that, he has no destination in mind.

Alone with his thoughts, Sprout is suddenly approached by a mysterious force that offers to be his friend. And this "friend" quickly convinces Sprout that his former friends can no longer be trusted, convincing Sprout to turn on them.

Imagine the shock of Sunny and the gang when Sprout suddenly morphs into a threat that Equestria hasn't seen in ages: The Pony of Shadows! And amidst the uncertainty of having to fight such an evil to save a friend, the five ponies receive help from the most unlikely of faces.