Sixteen-year-old Katelyn, who has been subjected to her mother's "wanderlust" all her life, discovers that Mom might not be who she says she is, and that someone is hunting them both.

Fourteen-year-old Sparrow Cooke of Brooklyn has always been the kind of child who prefers reading books to playing with friends (not that she has many of those), and since fifth grade the one person who seemed to understand her was the school librarian. So when Mrs. Wexler was killed in an accident Sparrow's world came apart, and when she was found on the edge of the school roof everyone assumed that it was a suicide attempt, which Sparrow denies,...