Woodbury has fallen. Underground, in a labyrinth of ancient mines and tunnels, Lilly Cole leads a group of old people, misfits and children as she fights to build a new life. But Lilly still has a secret desire to free her beloved city from the bloodthirsty hordes. And somewhere far away, in the midst of the growing tide of walkers that flock from everywhere, the mad preacher Jeremiah Garlitz is rebuilding his army of followers using a diabolical secret weapon. He plans to destroy Lilly and her team - the very people who destroyed his previous cult. And now Jeremiah for the first time has the opportunity to burn a hellish brand on the skin of the underground inhabitants...