After the Zs are cut free and dispatched, the gang meets a few of the gun-toting locals, who claim their town was overrun by the Red Hand, a crazed group of vigilantes who take their orders from a mythical figure known as 'Escorpion.' Say, didn't Hector used to call himself that ...?
Just then, the Red Hand attacks and the gang retreats to an abandoned novelty factory, where Hector figures this Escorpion is either someone impersonating him or just adopting his former villainous brand.
Upon discovering a wounded Red Hand member, Roberta asks the locals, Clive and Ryan, why their town has been targeted by this gang. Apparently they kind of had it coming, as they robbed the Red Hand of their food supply, prompting the exclamation of THIEVES back at the bridge.
The Red Hand attacks again, storming the factory with molotov cocktails and Zs strapped with dynamite. Roberta almost buys it in the resulting explosion, after which Clive and Ryan notice the tattoo on Hector's arm that identifies him as Escorpion.
Murphy's been feeling weak due to all the blood he's been donating to the research, and Merch informs him that he needs periodic shots of the original Z-virus vaccine or else he'll end up like Patient Zero back in Colorado (remember him from Season 1? He kind of looked like a Z version of The Fly).
Dr. Merch injects 10K with the original vaccine, which she's been secretly taking herself. It frees them from Murphy's control! She and 10K plan to destroy the Blend Vaccine and get the hell out of there ...
... though Murphy gets wind of their treachery and gives Dr. Merch a fresh mind-controlling bite. Before Murphy can test the Blend Vaccine on him, 10K makes a run for it with a satchel full of the original vaccine ...
Finally, Dr. Merch takes desperate measures to escape Murphy's control once and for all. She wanders into his Zombie Moat and stabs herself with the vaccine, causing the Z's to swarm and overtake her as Murphy screams in protest. Whoa!