For Mack McKinley and his team of GhostWalker killing machines, urban warfare is an art form. But despite a hard-won knowledge of the San Francisco streets, Mack knows from experience how many things can go wrong. Danger is part of the game -- and he's come face-to-face with a woman who can play just as tough. Jaimie has a sapphire state so potent it can destroy a man. And she's back in Mack's life to take on an enemy that could destroy them both.