"No matter what anyone tells you, I'm real. That's what the note says that Max finds under his keyboard. He knows that his best friend, Josie, wrote it. He'd know her handwriting anywhere. But why she wrote it--and what it means--remains a mystery. Ever since they met in kindergarten, Max and Josie have been inseparable. Until the summer after fifth grade, when Josie disappears, leaving only a note, and whispering something about “whatnot rules.”...