Black (The Firebrand Trilogy)

Scout knew she only had a handful of days left before she went Gray, changing into a creature that was no longer human. After witnessing the horror of her friends and family going Gray, she was devastated when her own inevitable transformation began. But when that didn't happen, Scout realized she was gaining powers that not only insured her survival, but allowed her to cross the flooded wasteland in search of her brother.Together, they must find a cure to prevent everyone they love from turning into monsters. But they will need help, and whether it comes from the brilliant, enigmatic boy named Google, or from the mysterious man who has somehow resisted going Gray, she knows one thing for sure: she is humanity's last hope.