This summer the Penderwick sisters have a wonderful surprise: a holiday on the grounds of a beautiful estate called Arundel. Soon they are busy discovering the summertime magic of Arundel's sprawling gardens, treasure-filled attic, tame rabbits, and the cook who makes the best gingerbread in Massachusetts. But the best discovery of all is Jeffrey Tifton, son of Arundel's owner, who quickly proves to be the perfect companion for their adventures.

The icy-hearted Mrs. Tifton is not as pleased with the Penderwicks as Jeffrey is, though, and warns the new friends to stay out of trouble. Which, of course, they will--won't they? One thing's for sure: it will be a summer the Penderwicks will never forget.