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."

But why would Max ever think that Josie wasn't real? And what are whatnots?

As Max sets to uncover what happened to Josie--and what she is or isn't--little does he know that she's fighting to find him again, too. But there are forces trying to keep Max and Josie from ever seeing each other again. Because Josie wasn't supposed to be real.

This middle grade thriller from Margaret Peterson Haddix delves into the power of privilege, the importance of true friendship, and the question of humanity and identity. Because when anyone could be a whatnot, what makes a person a real friend--or real at all?