What could have happened if Nightmare Moon had won over Twilight Sparkle and her friends? The tome Princess Celestia gives Twilight explains what she saw while using a spell. It shows a new threat to Equestria, as well, and Princess Celestia said this story has no happy ending.

Story Two of the Haven Trilogy, a partial sequel to Solar Flare concerning the second tome Twilight Sparkle received. I don't feel this is close to the best I could do, considering that when this was written, I was suffering from an immense case of Writer's Block.

http://www.equestriadaily.com/2011/06/story-solar-flare.html

SOON TO BE REWRITTEN