Review:
Holly is a young girl who is visiting her great-aunt during summer vacation. At some point earlier in the series, I'm guessing she must have gone exploring or something and figured out how to visit the magical world of Pony Island. In this book, she goes to Pony Island to meet Puck, her fairy pony friend. They're having a picnic together when they hear someone crying for help. It turns out it's a unicorn named Willow who's being attacked by several bad fairy ponies. Shadow, the ringleader, is preparing to do a spell that will give him unicorn powers and allow him to take over Pony Island. He stole the first few ingredients from Willow, and now he plans to trick the Unicorn Prince so that he can get the final ingredient.
I was told it wasn't necessary to read these books in any particular order. A bit of searching tells me that this is probably Book 5 in the Fairy Ponies series, although the only thing I felt I was missing out on was how Holly found Pony Island in the first place.
