The book is Blackwood by Gwenda Bond and the artwork is by Steven Wood. Apparently, it's about Roanoke Colony. From the blurb:
Miranda, a misfit girl from the island’s most infamous family, and Phillips, an exiled teen criminal who hears the voices of the dead, must dodge everyone from federal agents to long-dead alchemists as they work to uncover the secrets of the new Lost Colony.
Sold?