The next Best Young Flyer's Competition is coming up, and after being convinced by Rainbow Dash, Twilight Sparkle decides to join. But when she and Soarin begin to have a relationship, fate has other things in store for the princess...
From the darkest shadows of Equestria, an ancient evil emerges, keen on destroying the Elements of Harmony. The Princess of Friendship must take her ultimate test if she is to subdue this menace. And she must fight against the corruption of the Rainbow of Darkness that threatens to consume her soul...

Part of the Light and Dark Trilogy.