Sgt. McLaren is orbiting around a world known as 'Equis I' preparing for the mission of his life.
His mission is simple. Infiltrate the Equestrian military, rise to the highest rank possible, and await further orders.
Simple indeed... All he is required to do is give up his body, identity, dignity, friends, family and the rest of his life... all to play the role of an earth pony who was going to rise from being a recruit to being a powerful authority figure in a society completely alien to him.
Simple indeed...
Warning, contains lots of cursing.