This is the sequel to 13 Little Blue Envelopes. I prefer the first book but this was a good way to end the story :-)
Ginny Blackstone thought that the biggest adventure of her life was behind her. She spent last summer traveling around Europe, following the tasks her aunt Peg 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 it was supposed to end.
Months later, a mysterious boy contacts Ginny from London, saying he's found her bag. Finally, Ginny can finish what she started. But instead of ending her journey, the last letter starts a new adventure--one filled with old friends, new loves, and once-in-a-lifetime experiences. Ginny finds she must hold on to her wits . . . and her heart. This time, there are no instructions.