Who or what is the mysterious organization known as A.T.A.C.? And how are Frank, Joe, and even Fenton Hardy involved? Are the Hardys leaving Bayport forever? How has Laura Hardy"s life changed? Why is Aunt Gertrude acting so strange? Where"s Iola and Callie? Uncover the clues to these questions and more as Frank and Joe take to the skies to crack a diamond-smuggling team of sky-divers and then encounter a young woman whose identity has been stolen - literally! Or at least that"s what a young woman claiming to be Joy Gallagher claims - that another girl is now living her life, with her friends, her family, and in her body! Action, thrills, and lots of mystery!