M. T. Anderson meets Cory Doctorow in this teen debut from #1 New York Times bestseller Sean Williams, who also coauthors the Troubletwisters series with Garth Nix.

When a coded note promises improvement—the chance to change your body any way you want, making it stronger, taller, more beautiful—Clair thinks it's too good to be true, but her best friend, Libby, falls into a deadly trap.

With the help of the school freak and a mysterious stranger, Clair races against the clock and around the world to save Libby, even as every step draws her deeper into a deadly world of cover-ups and conspiracies.

Action and danger fuel this near-future tale of technology, identity, and the lengths one girl will go to save her best friend.