Jem's world has been turned upside down by a family crisis, and then it gets worse. Just when it all seems too hard, along comes Ella, Jem0's great-aunt, who's also a solo round-the-world sailor. She decides that what Jem, his sister Maddy and brother Tyler need is a sea change. But is seasickness the only thing that Jem adds to his list of woes? What's the mystery that Ella is chasing? Why does Jem keep having strange and troubling dreams, and what could they mean? And who is stalking them all?