1000 years ago, Discord fought a battle against the Royal Sisters Celestia and Luna... and won. He locked them away in the sun and moon respectively, and has reigned as king, shrouding Equestria in chaos and darkness. For 1000 years, the ponies of Equestria suffered, learning to live by stealing, lying, being greedy and angry, and yes, even at times... by killing. This is what ponies know- this is their life. However, there is hope... an unknown hope, deep beneath Canterlot, in the Canterlot caves. There is a secret community there, called the "Harmony Underground". A Unicorn by the name of Twilight Sparkle, who has lived in safety of the "Harmony Underground", finds out about the terrible and harsh outside world, as well as the true horror of Discord's rule. Now, there is only one thing she has set on her heart- to stop Discord, and bring peace and harmony back to the land! How will she do this? By finding and utilizing the ancient artifacts known as the Elements of Harmony! She just has to find them, and then figure out how exactly they work...
(Cover art not mine, also I do not own MLP:FIM.)