While cleaning the library Spike finds a secret door that holds an ancient artifact. While investigating they accidentally trigger the device and they change bodies. They are stuck that way until the next day. If Rainbow Dash fails to bring back a special ingredient to make the device work, the change will be permanent. Trouble is she has Fluttershy's body and a long flight ahead of her. Meanwhile the rest of the Mane 6 must do each others jobs since none of them want the rest of the town knowing what happened.