In the epic adventure of Z is for Zombie, this, sixth book acts as a kind of reboot for the ongoing post-apocalyptic drama. What Lies Beneath is the tale of some characters we have already met and their back stories as well as some new characters. A little group of young people find an experimental inoculation that will prevent them, if bitten, from turning into one of the shambling dead. Will they take the shots and make themselves immune or will they fight to remain fully human? What does the inoculation mean to mankind? Hannah come into her own as we learn how she grew up and how she was inoculated with the Red hybrid strain against her will. When she takes revenge, it is a shadowing of what she had to do before, in the first days of the outbreak, but it defines who she becomes, Meetin Hannah before the outbreak, we learn what motivates her, what scares her, and what she wants more than life itself. Len, the strong former Marine who carries a terrible secret from his past that haunts him, reveals what he was forced to do before the outbreak and why his heart still aches.