A human, scorned by the ponies he thought were friends, finds his way to the railroad tracks at night. As any sane pony will tell you, never travel the tracks at night. You just might not come back the same.
Tirek has taken over Equestria. But Equestria has some powerful allies. Allies in the form of a squadron of US Air Force A-10 Warthogs, who don't take kindly to allied nations being invaded.