When a colt gets his answer to "where do babies come from?" he's fine. He doesn't need any more answers on the topic... Except when he gets pulled into another world. In that case, he wonders where human babies come from.
Sunset Shimmer finally returns home to Equestria to right her old wrongs, unfortunately the sins of the Human World follow her back and put everypony in Equestria in danger.
A year after the battle of the bands, graduation nears, a familiar face returns, a pure heart is corrupted, enemies become allies and the fate of all reality hangs in the balance.