When eight children who have a long summer in the country before them learn that their favorite playground, Invisible Island, may contain a real buried treasure, a treasure buried back in the seventeenth century, they naturally lose no time in idle dreaming. Even Sweet William, the enormous yellow cat, pricks up his ears.

Everyone has a theory. No sooner is one perfect clue proved useless than three other reasonably good ones pop up. Yet, if one of the intrepid searchers had not sat down very hard in a briar patch, this fascinating story might have had a very different ending and the foresight of a little girl back in 1650 might never have been proved. Though a sequel to The Invisible Island, the present story is thrillingly complete in itself as new characters join the original group on Invisible and help launch their latest adventure.

From the dust jacket