When Twilight finds a new spell in a book, she is so interested in what it would do that she casts it immediately, without realizing that the window was open or that Apple Bloom, Applejack, and Big Mac were right outside.

When the three Apple siblings come to, they find that somehow, they have swapped bodies, and that they need to get the counterspell before things really get odd.

Rated teen for suggestive material.