(Note: This story has been declared by the writer as "non-fanon" but is being kept for scientific and nostalgic purposes.)
When Night Mist goes missing, Sharp Wing and Frazzle Spark make like their detective friend and launch an investigation. Along with help from Twilight Sparkle and some of her friends, they begin to unveil a vast conspiracy that causes Sharp Wing to wonder if he ever truly knew his friend at all.
Special thanks to PixelBoltStroke for providing the cover art. You can check out more of his stuff at http://pixelsboltstroke.deviantart.com/