Spy series can be extremely complicated to follow. They are wholly based on secrets, deception, and complex action plans, so sometimes what happens is hard to understand. In Citadel, the spy story which landed on Amazon Prime in April 2023, there are two secret organizations, Citadel and Manticore. According to how the plot has evolved so far, a mole inside Citadel helped Manticore take down the good agents worldwide. What do we know about this mole, and what’s the motive? Let’s provide some answers based on what the series exposed until now.
You can watch the official trailer for Citadel here on Youtube.
Citadel plot explained: Manticore and Citadel
In the plot of Citadel, the 2023 TV series on Amazon Prime, we understand the main organizations in the game already in the first episode. On the one hand, there is Citadel, an international organization that monitors the activities of all national secret services worldwide. Citadel’s mission is to prevent the secret services of any nation from driving the course of history, plotting events to their advantage. Therefore, Citadel is the structure that defends the world from evil individuals.
But someone wanted Citadel out of the game. That’s why they founded Manticore, an evil organization that intended to take down Citadel completely. One by one, Manticore killed most of Citadel’s agents in all corners of the world. Among Manticore leaders, we have Dahlia Archer, the U.K. Ambassador to the United States.
What we discover at the beginning of Citadel is that Manticore didn’t do everything on their own: there was a mole inside Citadel helping Manticore’s agents in their evil plan to erase Citadel. The central mystery in Citadel’s plot is the mole’s identity and motives: who helped Manticore destroy Citadel, and why?
Episode 4 of Citadel shows how, ten years before, Mason raised his suspicions about Brielle/Celeste: she was an old friend of Nadia who entered Citadel’s Tier-One missions, becoming a double agent. At some point, Mason orders her extraction from the mission and interrogates her about the Oz-Key she was supposed to steal. Her answers don’t seem to clarify, and Mason suggests the backstop procedure on her: she will lose her memory and live out of Citadel as Abby, an anonymous person who doesn’t know anything about secret services of any kind. Ironically, Abby marries Mason after he loses his memory as well.
In that episode, viewers could end up assuming Brielle/Celeste is the mole who helped Manticore take down Citadel. But we discover the truth from Spencer: he listened to a communication that reveals how Nadia ordered to conceal the Oz-Key behind Brielle’s shoulders. Spencer informs Mason about it, implying that what he did with Brielle served as a distraction: according to his theory, Mason believes Nadia is the mole, but since he loves her, he wants to mark Brielle as the traitor, so nobody will ever suspect Nadia.
Based on this discovery, we now know that Brielle/Celeste/Abby wasn’t Citadel’s mole. The suspicions went then on Nadia: she could be the mole who helped Manticore take down Citadel, and some of the flash-forward scenes we saw so far could confirm it. In Episode 5, though, we discover that Nadia wanted to leave Citadel and take care of her daughter. She had an agreement with Rahi Gambhir, Nadia’s father, who works for Manticore. So Nadia wanted to be out and care for her daughter, that’s the only reason why she left: she had no reasons or intention to take down Citadel.
Who is the mole in Citadel?
Let’s have this important point of Citadel plot explained. The answer to this question is revealed in the last episode of Season 1 when Mason recovers his memory: it was Mason Kane disclosing to Dahlia the information about all Citadel’s agents’ locations. Dahlia is his mother, who left Mason when he was a little kid after a bombing that killed his father. Dahlia left, leaving Mason with his grandmother, but once he grew up, she gave him availability to help him if needed. Mason asked her for help after Nadia left Citadel, and Dahlia found her for him. But on that occasion, Dahlia reveals the truth about how Mason’s father died and convinces Mason to take down Citadel. “Someone needs to do something, or Citadel will keep taking the people we love without consequences”: this was the motive of the betrayal.
Citadel had a surprising ending that needs to be explained separately, though: here is everything you need to know.