Liv confesses to cheating on Justin, causing him to break up with her. Major, devastated by Natalie's death, asks Chase Graves to turn him. Liv and Clive suspect Chase of using his dog to spread the Aleutian Flu virus. He's innocent, though, it's actually his Number Two, who's leading a faction opposed to the island project. She's the one responsible for his brother and sister-in-law's deaths. Chase kills her and three of her supporters, but Cary claims there are more of them out there. The Mayor declares a mandatory vaccination against the new flu strain, but Liv discovers that Fillmore-Graves soldiers are adding a few drops of their blood into the vaccine for the purpose of turning most of the city's population into zombies. Revealing that Chase has decided to go ahead with Carey's plan. Liv knowing that Clive is going for a vaccination shot desperately calls Clive to warn him. Clive barely manages to avoid being turned, but Dale, who now knows the truth about zombies and who wishes to resume her relationship with Clive, takes the shot before Clive can warn her.
Liv goes to Johnny Frost (now an anchor) and explains why he's suddenly craving brains. She has him broadcast the truth to try to save Seattle citizens from being turned. Liv confronts Graves when he shows up the station, asking why he infected so many people. Chase says the explanation is in his own message, one he sends to the nation, requesting the brains of the deceased to feed the Seattle zombie population because a fed Zombie is a happy zombie, implying that it would be beneficial for the United States ensure a steady brain supply to Seattle's newest Zombie citizens lest something unfortunate happen. At a feeding post, a mob of humans tries to storm Justin and Major's squad, forcing Justin to give the order to open fire to protect both themselves and the new zombies.
Ravi reveals that he has developed a vaccine for the zombie virus and asks Liv to scratch him to test it.
- Anti-Climax Boss: Carey claims that her group of traitors are everywhere. However, after Chase guns her and her mutineers down they are never seen or heard from again.
- Boom, Headshot!: How Chase Graves deals with the traitors within the company, although to be fair his initial idea is to simply freeze his Number Two until he can figure out a more fitting punishment. She forces his hand.
- Does This Remind You of Anything?: When Peyton tells Mayor Baracus about the reveal of zombies in Seattle he is reading to some school children.note
- Fade to Black: The episode (and season) ends before we learn if Ravi's vaccine works.
- Healing Factor: After the end of the Masquerade, FG mercs go around hospitals and turn terminally ill patients (with their or their loved ones' consent, of course) in order to save them.
- Star-Crossed Lovers: Just when Clive finally reveals the truth to Dale and has gotten back with her, she is infected, so they're no longer able to truly be together without her turning him.
- The Unmasqued World: Chase decides to implement the rebel faction plan to infect Seattle instead of stopping it, using his own men to carry it out and in the process intentionally turning tens of thousands of Seattle citizens without their consent. Liv has Johnny Frost broadcast the truth to the city, while Graves himself sends out a message to the world.
- Your Approval Fills Me with Shame: Liv seems perfectly willing to wear makeup and a wig, making her seem human. However, after Chase compliments Liv for getting with the program, by changing her look after he infects thousands of Seattle citizens with the zombie virus, she shoots him a look of disgust and later reverts back to her Zombie look in defiance.
- Your Cheating Heart: Justin dumps Liv after she tells him she slept with Chase Graves. She tries to excuse it by blaming Katty's brain, but he's having none of that. Later, when he spots her sneaking into their staging ground, he calls the other mercs on her.