It's all about surveillance. Back at Quantico, the NATS learn the art of surveillance. Miranda is sick of her son lying to her, so she gives the NATS the mission of surveilling her, hoping to learn something about her son, Charlie.
During the surveillance mission, Alex overhears a conversation between Ryan and Liam and learns about Ryan's mission. Alex is done with Ryan, and she's now spying on Liam.
Caleb is back and the head of the D2 surveillance task group looking through social media posts for Alex. That's right, Caleb is an FBI Agent working in D2. However, Simon manages to get Alex into Caleb's computer so she sees what he does.
Caleb trashed surveillance footage, and Alex thinks it is to cover up the fact that Caleb was there. Turns out, Caleb was looking for his dad to find out who he was having an affair with. It's Shelby. This just got a lot more awkward.
There is something else that Caleb spotted on the Grand Central footage - one of the twins, days before the bombing. Now we've got ourselves two new suspects.
Back at Quantico, Simon gets closer to Raina, and it leads him to discover the twin secret.