Princess Celestia was actually never at the Seapony's realm for a vacation, she was kidnapped by somepony...or ponies. It's up to Rainbow Dash and her sisters to find her, however, the obstacles ahead are unknown and dangerous.
The elements of harmony hear of a prophecy telling of a few new ponies that will become the next elements of harmony. Who? The children of of the main six.
Luna met a pony named StarBurst. They became closer as friends. Then they set off for an adventure. Strange things has been happening along the way. Then both ponies had reached what's beyond the forest. Danger is in every corner.