When Happy Go Lucky, a young quarter pony, is moved from his home to the stables at Big Apple Barn, endless adventures await him!

Just when Happy Go Lucky is starting to feel at home at Big Apple Barn, everything changes. There is a new pony in the barn: Sassafras Surprise, otherwise known as Sassy. Everyone wants to learn more about her.

Suddenly, Happy's friends are not around as much. They're all spending time with Sassy, instead! Even worse, Sassy doesn't seem interested in being friends with Happy at all. What's a pony to do?