On Quantico Season 1 Episode 20, the NATs are taken to a local field office to shadow real agents working real cases. The agents will be evaluating the trainees. All the NATs we care about are sent to the Richmond field office. 

For Raina and Nimah, this field trip is a test. There's one agent who knows their secret. S/he is their contact. Nimah and Raina have to figure out who that person is. They guess wrong. However, they manage to get away with it, and now they have been given the chance to infiltrate an important and deadly terrorist cell.

Shelby has a change of heart about her top three choices for assignment. She decides to pick field offices that are close to the Canadian Border, so she can visit her parents. Caleb comes clean to Iris and tries to get her to talk Shelby out of it. Iris does her best, but when Shelby reveals that she's leaving the FBI so she can be with her parents, Iris tells Shelby the truth about her parents, Caleb, and how he's been lying to her.

In the present, Alex is on the run yet again from the FBI. She and Shelby try to track down Simon. In the process, they find Drew. He claims that he was a victim of the The Voice, and that The Voice is Ryan Booth. Drew gives Shelby and Alex a flash drive that he says will find proof of the voice altering software on Ryan's computer.

Ryan catches Alex using his computer at the FBI office. It's time for close quarters combat. She tells him about Natalie, and his reaction makes Alex think that Ryan's innocent.

Then who is The Voice? Why none other than Drew. He planted a manifesto blaming Ryan via the hard drive. 

Now, Alex is driving around in Ryan's truck with Drew threatening to detonate the nuke if Alex doesn't do exactly what he says.