The terrorists responsible for the bombing of Grand Central Station finally reveal themselves, but instead of answers, more questions remain. While back at Quantico, the recruits receive a well-deserved few days off for the holidays, but not everyone is oh so merry when secrets are revealed and lines and blurred.

Alex finds herself in the middle of a congressional hearing to testify about the terrorist bombings. Convinced Elias didn’t act alone, she is determined to find answers and the truth. While back at Quantico, a new group of NATS join Alex and her classmates, causing tension and competition between the groups of trainees.

A terror cell tries to infiltrate Quantico, forcing Miranda and Liam to pay a deadly price. While in the future, Alex continues to get instructions from the terrorist – only this time, it’s Claire Haas’ life that hangs in the balance.

At Quantico, the NATS are given a training exercise that hits too close to home for Shelby. While in the future, Alex finds an unlikely ally in Hannah, as she continues to try and stop the terrorist from striking again.

At Quantico, the NATs look into each other’s background to determine who gets high-level security clearance, and in the process Alex, Shelby and Iris learn some surprising truths about Drew, Will and Caleb. Meanwhile, in the future, Alex contacts Claire Haas (guest star Marcia Cross) in order to find her missing friends and is shocked when she discovers what happened to Cale.

The NATS are excited that graduation is near as they prepare to leave Quantico and head out into the real world for their new assignments. In the future, Alex learns someone she cared about at Quantico is not who they seemed to be, as she finds herself at the heart of another possible attack.

It’s graduation day for the NATS of Quantico, while, in the future, Alex and her team find themselves head-to-head with the terrorist.