The BAU was called to investigate two murders committed against members of feuding families
The first murder was done through the use of a bear trap lined with barbed wire. The second was done when the victim was strung up in his doorway by a barbed wire noose, after which his head was twisted completely around.
Since the families' feud first started decades ago because of competing interests in the production and sale of moonshine, the BAU suspected that in present time their conflict had graduated to the production of meth.
A third family member was killed when the Unsub put a barbed wire noose around the victim's neck, and attached it via chain to a piece of garage furniture. The Unsub then attached the other end of the chain to a car bumper, which he used to drive away fast, thereby decapitating the victim.
The families both thought that someone from each side was targeting them.
The BAU figured out that the family businesses had nothing to do with meth, but involved the production and sale of biofuel. In fact, the feuding interests dynamic was misdirection, as the Unsub had no interest in any of it.
The Unsub kidnapped the matriarch of one family - Cissy Howard - and forced her to confess to her past. At the same time, Hotch interviewed the patriarch of the other family - Malachi Lee - and heard him relate the same story as the Unsub was hearing.
It turns out that Cissy wasn't her real name. In fact, she had changed it years ago, after giving birth, so as to escape her family. In fact, she and Malachi Lee were actually sister and brother, who had committed incest all those years ago. The product of their union was a deformed baby - who turned out to be the Unsub.
After Cissy's confession, the Unsub decided to kill her. Knowing that the FBI would come looking, he set her up by a tree.
Blake found her there, but before her backup team could arrive, the Unub attacked Blake, causing them both to go into a nearby lake. She managed to get off a few shots from her gun, alerting her team that she was in trouble.
When the team got to the lake, they couldn't find her. Blake finally emerged from the water, screaming at her team to shoot into the water. They unloaded about thirty bullets and were sure they had got him. Rossi called for the lake to be dragged.
Cissy and Malachi left the police station, only to be confronted by their families, who were now suspicious about their secret.
The episode closed with a scene involving a young couple coming to a cabin in Kentucky. They were confronted by the Unsub who demanded their car keys.