Upper Elementary Book Review discussion

It's book is about Margret and Sophie, 12 and 8 year old sisters who live with their mother, Lizzy. Their father drowned four years ago, and their mother will not speak of it. They live in a cloud of the depression that surrounds their mother. One day, they travel to an island and place a For Sale by Owner sign in front of an old run-down mansion the girls had never seen before. And Margret finds a mysterious package on the back porch of the mansion that Lizzie had returned unopened. I love this book, because it pulls the reader in quickly, and contains mystery upon mystery. It is also told from the point of view of Boyd, the 12 year old boy who lives next door the the mansion, and the editor.