All manner of things come to a head in episode 5, Naomi. The title character is a girl who begins the episode on a school field trip to a nuclear power plant. Because a Traveler team is waylaid and can’t carry out the Director’s plan to stop a nuclear explosion, Naomi is pressed into service as a super messenger, with her brain running a program that allows her to shut down the hack that was going to cause the nuclear power plant to go critical and kill tens of thousands.
The Director’s program doesn’t leave Naomi’s head as expected, so she’s left speaking code at inopportune moments. Grace, with the support of Mac’s team, is called in to fix the issue. It’s proves to be a very stubborn program.
Issues are also coming to a head for David and Kat, in the aftermath of their kidnapping and the strain it’s put on their relationships.
Kat insists that Mac meet her at her therapist’s appointment, so that they can work on their issues. He can’t find the emotional honesty that David and Marcy have, that allows them to work around the secrets Marcy needs to keep. Instead, Mac keeps piling on fresh lies and defensiveness. When he gets called back to ops, he becomes even more aggressive and defensive, in order to give himself an excuse to get out of the meeting. But he actually means everything he says.
David decides that he needs to take protecting himself to the next level, which scares Marcy. After David spent season 2 worrying that he could lose Marcy again at any time, in season 3, it’s Marcy’s turn to worry about losing David, and her turn to go overboard with it. David goes overboard himself, because this is about more than just keeping himself physically safe.
This is about protecting his image of himself as a man and as someone who can move through the world with the automatic protections that men take for granted. It’s untenable for him to worry about becoming a victim of violent crime every time he leaves the house, so he needs to confront it, and win, to calm his nerves, even if the confrontation is purely symbolic.
Imagine if he had to consider his chances of being raped every time he went out alone after dark.