Prime Video's ambitious spy thriller Citadel returns for a second season this week, and if you need a refresher on the intricate web of betrayal, memory loss, and family secrets, you're in the right place. The first season, which launched in 2023, introduced us to the fall of the elite Citadel agency and the rise of its evil counterpart, Manticore. Since then, the franchise has expanded with spin-offs Citadel: Diana and Citadel: Honey Bunny, but the original story—centered on agents Mason Kane (Richard Madden) and Nadia Sinh (Priyanka Chopra Jonas)—is about to get a major continuation.
Season 1 kicked off with a heart-pounding train sequence that saw the destruction of Citadel, with Mason and Nadia seemingly killed. But as we soon learn, they survived—only to have their memories wiped and live separate lives. Their former handler, Bernard (Stanley Tucci), pulls them back into the espionage world to stop Manticore from acquiring a powerful device called the Oz Key. The season becomes a race to uncover who betrayed Citadel on that fateful train.
Nadia and Mason's Daughter Changes Everything
One of the season's biggest reveals is that Nadia and Mason have a daughter together. Nadia, who regains her memories mid-season, had kept this secret because Mason once accused her friend Celeste (Ashleigh Cummings) of stealing the Oz Key—even though he knew Nadia had destroyed it. That accusation led to Celeste's involuntary memory wipe, creating a deep rift of mistrust. In the finale, the couple must work together to save their daughter, who has been kidnapped by Manticore—specifically by Mason's mother, Dahlia (Lesley Manville). Dahlia uses the child as leverage to retrieve five nuclear cores from a Russian submarine. The duo manages to secure the cores but ultimately saves their daughter without handing them over, leading to a successful mission. By season's end, Nadia is cleared of suspicion as the mole and reunites with her daughter, but the question of who truly betrayed Citadel remains.
Mason's Shocking Truth: He Was the Mole
In the final moments of Season 1, Mason injects himself with a memory-restoring serum and discovers the devastating truth: he was the mole. Eight years prior, his mother Dahlia manipulated him into believing Citadel was the enemy after his father died in a botched Citadel strike that killed 157 civilians. Fueled by grief and anger—and reeling from Nadia's disappearance and the revelation of their child—Mason handed over documents exposing every Citadel agent, enabling Manticore's attack. Now, as Season 2 begins, Mason is trapped in a waking nightmare: he remembers his betrayal, but he lies to Nadia and Bernard, claiming the serum didn't work. Meanwhile, his wife Abby is actually Celeste, the friend he condemned to a memory wipe years ago.
Manticore's Threat Looms Large
Despite losing the nuclear cores and her bargaining chip, Dahlia fakes her own death by blowing up her house to avoid facing Manticore's leaders. Her future role is uncertain—she could become an ally on the run or a vengeful enemy. Either way, Manticore remains a formidable threat, and the stakes are higher than ever. According to the trailer, a new danger is also emerging, adding to the tension. As the operatives navigate Mason's secret and the fallout of his past, Season 2 promises an intense, gripping ride.
For more on what to watch, check out our list of Prime Video Shows That Demand a Binge-Watch and the Best Shows to Binge on Prime Video This May 4, 2026. And if you're a fan of the genre, don't miss our Forgotten Gems: 5 Near-Perfect Thrillers That Deserve a Second Look.
Citadel Season 2 premieres May 6 on Prime Video.
