An evil force has awakened in Equestria and in an attempt to outwit said force, Princess Celestia summons a being from another world. Plucking them from their own and transforming them into a pony. This poor soul has unwittingly become the linchpin in Celestia's convoluted plot to defeat evil.
The soul's name is Carl and he has absolutely no interest in becoming a hero for some pony princess he only just met. He is rude, foul-mouthed, bad-tempered, sarcastic and overall... a total jerk. How a pony like him is supposed to save Equestria is anyone's guess...