I believe that blinking thing in her neck is one of the tracers. She dug one out of her leg in the earlier scene. The fatalistic realization is that, after this 40 minute chase and so much suffering and effort to fight, when she finally beats the dog, it shoots up a ball of those tracers. She’s doomed, and always was.…

Holy crap, the ending of this one hit me in the gut. Such a simple twist, but, wow. One noir-like shot of the contents of the box strewn about and I was a wreck. I think this was the high point (in storytelling, not mood) of the season for me.