One year after the events of Shattered Dimensions, Allen has returned to Equestria in hopes of peacefully living out his days with his friends, and plans on asking Princess Luna to marry him. Unfortunately, Allen's hopes are interrupted when Project G.E.M., a secret initiative from Earth, breaks the boundaries between the two dimensions, which subsequently awakens a warlord from the pony-human war thousands of years ago.
Now, Allen must deal with the threat of attacks from his new enemy, preparations for the upcoming Crystal Fair, and an unexpected visit from someone he never thought he would see again: his father, Robert Greathouse.
A young boy attempts to take his own life, but after being unsuccessful in his attempts, he is transported to a world where he learns that maybe life isn't that bad, and friends can be right around the corner.
Allen Greathouse faces his biggest challenge yet when humans breach the boundaries between worlds, which subsequently awakens an ancient and powerful enemy.
Two months after the union of Allen and Luna, Drayke Blackwood is brought back to Equestria to investigate the crystal prince's disappearance.