Strange discoveries. Mysterious twitching. The curious feeling of being watched. And a sudden urge to sing. Something's happening to Applejack, and no matter how often she laughs, this is no laughing matter!

Keeping in touch through letters, two friends become very close and maybe even more. After Twilight moves to Canterlot, to help the sick princess, she and Pinkie Pie discover a close friendship they never knew about.