This book is the 3rd of the "Swallows and Amazons" series of 12. While not our favorite, it is an interesting story and we certainly have enjoyed reading it aloud.What is so delightful about this book is again the joyful flipping from reality into imaginative play. The Walker children and the Blackett sisters are once again involved in a wild adventure. However this story is of a different type. Peter Duck the character was introduced in "Swallowdale", the 2nd book in the series. In that book, Peter Duck is an imaginary character invented by the children and clothed with stories that make him seem real. This book then is one of the stories that clothe the imaginary character! The adventure is told as though it is one the Walkers and Blackett's really had, but in reality it is a story within a story. After reading "Winter Story", the 4th book in the series, you realize that this sea yarn was probably spun over a winter holiday when the children were imagining a sailing trip to the Caribees with their very own salty sailor, Peter Duck!So this book is full of sailing, this time on a ship named the Wild Cat, after their lake island. Nancy and Peggy's Uncle Jim, whom they call Captain Flint (they are pirates, so he is given a pirate name also!) sails out with them as captain and Peter Duck as first mate. Chased by real pirates in the Viper, they sail to a treasure island to find a chest that Peter Duck saw buried there over 30 years ago.Who will find it first and who will make it back to port in one piece? That is the adventure to be read about!Great fun. A big recommendation to all... and.... there are 9 more books in the series!