Chaos overtakes the fort when one of Howie’s group turns and starts killing survivors. Howie and his team are blamed and shunned but carry on their search for fuel to run generators in order to carry out research on the dog.
When Marcy realises the infection can cure diseases, and realising she can be strong and good, she decides to head to the fort to hand herself in to be examined, too. Howie is only partially convinced of her good intent, and, despite their hatred of one another, there is an undeniably strong connection between them.
Meanwhile, inmates inside a prison start killing each other, and Fletcher, an ex-power-lifter, is turned, becoming the most evil undead yet known.