In the dark waters, you see a shape begin to take form. A hideous figure emerges from the swamp, and points to you with a single, calloused finger. "Hey mate, you going to finish that sandwich?"
When Twilight Sparkle decided to go to Moondancer's party instead of the Summer Sun Celebration, the entire world is thrown into disorder, and Lyra, Bon-Bon, Muffins, Octavia, Zecora and Pip are all that stand between Equestria and eternal night.
National Dash Parade Day. In celebration of Equestria's greatest hero. Of course, 104 years after the first one, some of the details of how it started have changed...