Basically it's a summer of re-living the survival skills of the first book, except they are in a barn on their grandfather's island. A captain and his so-called handyman live close by to help if anything should happen. But the handyman seems to know a lot, and the children find it hard to believe that he's only a handyman.
This book also marks the first appearance of Benny's friend Mike, who plays a pretty important role in some of the books to come. It also hints at the yellow house, which was what spurred the story of the third book (the first real mystery in the series).
Definitely should be read as part of the real Boxcar Children experience - not the foundationless fluff written by various authors of today.
One of the very rare orginal books, truly written by Gurtrude Chandler Warner, it follows the newest adventures of Henery, Jessie, Vilot, and Benny as they attempt to solve the mystery of the island's stranger who cannot reveal his identy to them.... This book is even more gripping and mysteryous than the forerunner, THE BOXCAR CHILDREN, and will delight those who consider themselves friends of the Alden family.
Also Reccomended: The Boxcar Children (#1), The Yellow House Mystery (#3), Mystery Ranch (#4), Mike's Mystery (#5), Blue Bay Mystery (#6), The Woodshed Mystery (#7), The Lighthouse Mystery (#8) Mountian Top Mystery (#9), Schoolhouse Mystery (#10) Caboose Mystery (#11), Houseboat Mystery (#12), Snowbound Mystery (#13), Tree House Mystery (#14), Bicycle Mystery (#15), Mystery in the Sand (#16), Mystery Behind the Wall (#17), Bus Station Mystery (#18), Benny Uncovers a Mystery (#19)