The Essence of Villainy is about(you guessed it) the essence of evildoing and how we perceive it. However, if you want a fancier summary...
"It is time for the final battle. The Dark Lord Gustav and the Paladin of Divine Lightning meet on the field before Castle Darkstead. Landscape-altering spells are wrought, and one of the combatants realizes a lack of preparedness for the fight. A forbidden spell is brought to play, and reality shifts.
Stuck in a new world, Gustav has to find that which he has lost - his capacity for battle. But stuck in the middle of wherever, how can he ever hope to rise again? And what if the battle isn't actually over yet?"