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.

Dexter and Harrison find themselves closer than ever over Christmas break. What kind of gifts will this father and son give to one another? But this brings this father and son into the crosshairs of a very violent and scary serial killer. Angela starts to wonder if Iron Lake is not the cozy and safe place she always thought it was.