After the shocking revelation of Abby's former identity, we learn of the past entanglements between Mason, Nadia and Celeste, and a horrific decision that reverberates still today. Meanwhile, Nadia and Kyle land at the Manticore compound in Morocco and risk their lives to free their fellow spy. But their hero's welcome is short-lived as they are forced to grapple with a dangerous accusation.

In the epic conclusion to the season, with one of their own being held hostage by Manticore, Kyle, Nadia and Carter risk everything to save them and thwart Manticore's plans to acquire nuclear weapons. As our heroes grapple with the nuclear threat, the identity of the mole within Citadel will be revealed, as will the awful truth that everything they know is a lie.