In book nine, a girl has mysteriously run away from home and her parents are frantic with worry. Can the Secret Seven follow the clues and catch up with the girl, or will Susie, Jack's troublesome little sister get in the way?...Solve the mystery!

Cover and inside illustrations are by the brilliant Tony Ross, illustrator of David Walliams's books. The story was first published in 1951. This edition features the classic text and comes with a Bonus Blyton section at the back with quizzes, puzzles and other bonus extras!