Secret Seven Win Through

In this book, the Secret Seven members are faced with the challenge of relocating their meeting shed after it is converted into a hen-house. Upon discovering an old summer house to use, they encounter a mysterious boy loitering around it. The Secret Seven must uncover his identity, as his peculiar behavior suggests he may be concealing something. Furthermore, they realize that their new meeting place is being used by someone else at night. With the help of Jack's little sister Susie, they are able to apprehend the intruder.