When Happy Go Lucky, a young quarter pony, is moved from his home to the stables at Big Apple Barn, endless adventures await him! When the spring festival comes to town, Happy Go Lucky and his friends can't wait to see what it's all about. But when Roscoe the barn mouse disappears, Happy worries that he's gone off to the festival alone. A trip to town could be dangerous for a tiny barn mouse! Can Happy find Roscoe before it's too late?