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.