Meet Liana, Musa's hard-as-nails second-in-command, and pssstt!: we think she might be Regan's mother. She's preparing what looks like massive amounts of weaponry for something called 'The Purge' ... and she's a bit miffed that Abby failed to deprogram Regan.
The Hunters are attempting something called 'the reversion process,' which seems to be essential to The Purge. It's not going well, as this poor creature is, per Musa, "stuck between Hunter and human."
Don't shoot! Per intel from Regan, Briggs and Flynn question Sterling Martinez, a research scientist specializing in skull and bone disorders whom the Hunters want to recruit to help with 'the reversion process.'
Abby calls and begs Flynn to rescue her from having to kill an innocent person right as he's about to take in Martinez. Of course, it turns out she's hiding mere feet away from Martinez's house, watching Flynn as she talks to him. Briggs tells Flynn that it's a ploy to lure him away so she can snatch Martinez ... and he's right!
Back at the ETU, Briggs confronts Flynn about his increasing drug use ... and informs him that the scar on his arm was also found on Jules and several other Hunter victims. They get in a big nasty man-fight that leaves Briggs unconscious on the locker room floor.
Jackson looks on as Regan and her father Ted have an emotional reunion. It turns out Finnerman had Ted locked up in a secure facility for the past six years. Ted reveals that Regan's mother tried to kill him ... and that she's Musa's right hand. We were right about Liana!
The hooded prisoner turns out to be McCarthy, who's been brutally tortured by Finnerman. When Jackson offers him some water, he overpowers him and escapes, killing the ETU guards and leaving Ted and Regan in the interrogation room. McCarthy on the loose again!
Musa threatens to ban McCarthy from The Purge due to his recent recklessness that led to the deaths of Tasha and his own child. McCarthy begs for forgiveness, which Musa seems to grant ... but you know McCarthy's got something up his sleeve.