Ginny Blackstone spent last summer traveling around Europe, following the tasks her aunt laid out in a series of letters before she died. When someone stole Ginny's backpack—and the last little blue envelope inside—she resigned herself to never knowing how the adventure was supposed to end.

Now a mysterious boy has contacted Ginny from London, saying he's found her bag. Finally she can finish what she started. But instead of ending her journey, the last letter starts a whole new one, and Ginny must hold on to her wits . . . and her heart. This time, there are no instructions.