It's for a Double Group Contest, more here: [link]
Princess Luna has been captured by the evil Chrysalis. Princess Celestia is very determined for her rescue. So she immediately make a plan: She organised the S.S.E.S.R.T. (Secret Solar Empire Spy Rescue Team), featuring the Main 6.
After that Celestia directly attack, with the most of her Soldiers, the army of Queen Chrysalis. In the mean time, the S.S.E.S.R.T. sneek in the Queen's Hive, and try to silently rescue Luna. The Plan working well, even though that they have to take care for one unexpected "want to rescue Luna too" filly.
This is the final moment, where the Team finaly will rescue Luna. Twilight is telling AJ to let Pinkie more down, so she can attack with her suprise pies. Rarity is preapering for the rescue too. She want to make a good impression. A lady can't look awfully, while saveing somepony else. Fluttershy is hideing, she want to be out from the fight. She even switch from tree to rock, so she can easily hide in the cave. And poor RD's job is to take care for the unexpected hero, who wanted to help too.
Will the plan work? Who knows?