Dexter is worried that a serial killer may have set its sights on someone he cares deeply about. So, he turns from predator to protector... a role he's not comfortable playing. Meanwhile Angela arrests someone from Iron Lake who may be the culprit of a cold case that is near and dear to her heart.  Dexter and Harrison run into some more bumps in the road in their relationship, leading Harrison to turn to a very dangerous person as his father figure.