Harper agrees to help Nolan take down Armstrong once he builds a circumstantial evidence case against the police officer. We have a flashback about Armstrong that shows he has been in the pocket of the Derian crime family for the entire series. Furthermore, he continues to stymie the investigation into Serj. Lacking any leads, Nolan consults with Rosalind Dyer who reveals that she found Armstrong's stash of cash, weapons, and evidence.
Nolan breaks into Armstrong's house and locates his stash before departing, but Armstrong sees him as he leaves. Armstrong alerts Serj Derian, who is arrested by the LAPD after they find evidence of his presence at a murder via Instagram. Armstrong invites Nolan back to his house, explaining that he got in too deep with the Derians once the costs for his deceased wife's medical bills became too much for him to handle. Armstrong then claims he plans to frame Nolan but loses a shoot out, causing him to tell Nolan he's left a bunch of evidence at his house.
Nolan rushes back to his house and finds the planted evidence just before the police arrive.
- Cliffhanger: The episode ends with police surrounding Nolan's home.
- Did Not Think This Through: Nolan going lone wolf in his investigation leaves him vulnerable to Armstrong's frame up attempt.
- Dirty Cop: Armstrong is revealed to be The Mole for the Derian mob.
- Frame-Up: Armstrong sets up Nolan as the Dirty Cop with Serj's help.
- Healthcare Motivation: Armstrong got into debt with the mob in order to pay his wife's medical bills.
- How We Got Here: We get a flashback to Armstrong's actions in the previous episode.
- It Gets Easier: Serj reassures Armstrong that killing becomes easier after this.
- The Mafiya: The Derian mob is a Armenian crime family.
- The Mole: Armstrong is in the pocket of the mob and is now willing to kill his fellow cops.
- Trapped in Villainy: Armstrong finds out there's no way out of The Mafiya's pocket.
