Twenty Years after Twilight was winged, she is the ruler of her own kingdom, a small island that mysteriously appeared off of Vanhoover named Equus, but something Twilight discovers on the island is more powerful than anything that has ever been recorded in Equestrian History. Celestia requests to Twilight that her and the citizens leave the island immediately. Twilight refuses her teacher's orders and the island mysteriously vanishes.
Five years later, Celestia and the remaning royal family finally find a pin-pointed location of Equus. They send Rainbow Dash, the element of loyalty, into the "invisible island" to try and convince Twilight to come back home.