Twilight has a problem on her hooves. An hour before Celestia was supposed to come to Ponyville for the Summer Sun Celebration, she's accidentally gone and killed everyone dead. As in, "dead as a doornail" dead. Now she's got to fix it before Celestia shows up and finds out.

Or, at the very least, make sure that Celestia doesn't know that they're dead.

Blame Blueshift for this.
Now with a sequel!
Now with a reading, graciously provided by Skijarama!