The first season of Citadel is over, finally giving us a breather after the Prime Video blockbuster spy show delivered us six episodes of non-stop drama, backstories and revelations about characters... with some action thrown in there for good measure.
Citadel episode 6 somehow has more secrets to lift the lid on, and to make heads or tails of it you're going to need to use the list on the right to catch up on past episodes too, otherwise lots of this won't make sense.
Episode 5 finished with Mason Kane (Richard Madden), Nadia Sinh (Priyanka Chopra Jonas) and Carter Spence (Osy Ikhile) being tasked with breaking into a nuclear submarine in order to deliver the nuclear cores to Dahlia Archer (Lesley Manville) in exchange for the safe return of their child.
This sixth episode of Citadel continues the series' tradition of jumping between different timelines with reckless abandon, so as a note, we've sometimes condensed different flashbacks and points into the same plot point in this recap, to help this article make a bit more sense.
Not watched the episode yet? Here's how to watch Citadel if you need help working out where to stream it.
*Spoilers for Citadel episode 6 follow*
The submarine heist
After a brief prologue following a young Mason Kane 30 years prior when he's a traumatized child in a Serbian hospital, and then sent to stay with his grandmother in Wyoming, we're back to the present. Kane, Sinh and Spence are being briefed on the mission they're carrying out for Manticore, which is to hack into a remote submarine, get it to the surface and then unlock Kane's biometric lock in order to steal the nuclear cores. All of this is in exchange for Sinh and Kane's daughter.
We also get to see a flashback of Kane originally doing this eight years prior, when he broke into the sub before. He was meant to pass over control to Citadel, but because they refused to tell him where Nadia was hiding, he added an extra biometric lock so he had control instead.
In the present, Kane jumps onto the submarine along with Davik Silje (Roland Moller), and as soon as Kane has unlocked the biometrics, Silje tries to throw Kane off the sub. Silje proceeds to hold the nukes hostage in revenge for Archer killing his brother, until she gives him a "seat at the table", but she refuses.
Sinh, seeing things are going wrong on the submarine, jumps onto it too — she extracts the cores while Mason fights and kills Davik, and Spence rescues them both.
Family reunions
In Spain, Nadia and Mason prepare to trade off the nuclear cores for their daughter, however it quickly turns into a shootout — thankfully the daughter is fine, despite being dropped from a motorway overpass, and they all escape unharmed.
Dahlia Archer realizes that things have gone wrong — rather than face the consequences, she fakes her own death by blowing up her luxurious mansion.
Eight years prior, we see Kane walking on a beach in London with Bernard Orlick (Stanley Tucci) who's apparently a keen detectorist. Orlick gives Kane a file showing that Nadia has run away to Spain and has her and Kane's baby. This is all it takes to stop Kane from pursuing Nadia, and he understands why she ran away.
The future of Citadel
Kane, Sinh, Spence and Sinh's daughter all flying in the jet to Citadel HQ in Utah, and we see it for the first time in the present. It looks like a warzone — but hiding out in the ruins are Abby Conroy (Ashleigh Cummings) and her and Kane's daughter. Reunions ensue.
Spence and Sinh are understandably concerned to find out that Kane's long-lost wife is in fact the ex-agent Celeste.
In the rubble, Spence finds a backup of Kane's memory vial, which would let him remember his true spy memories. Kane agrees to take it, and upon doing so immediately remembers what we've been learning through flashbacks all season: his love affair and child with Nadia, the fact that Abby is a former Citadel spy who he opted to irreversibly wipe the memories of, and one other thing.
In another flashback, Mason Kane goes to speak to Dahlia Archer just before the fall of Citadel. He asks her help in finding Sinh, and it's clear they already know each other. The reason why is quickly shown: she is his mother.
Archer tells Kane why she abandoned him when he was five: although he thought his father was killed by a Serbian insurgent, the truth is that Citadel killed him when they accidentally bombed a civilian building, and tried to cover it up. Archer asks Kane to provide her with Citadel's secrets, so they can bring them to the UK government and start an inquest — and Kane obliges.
Unfortunately, Archer was lying, and she instead provided the information to Manticore. So Kane was the unwitting mole in the end, not Sinh.
The season ends with a hint to the future of Citadel — not just with the core characters (except a mysteriously absent Orlick) in Citadel's former headquarters, but with a tease of another character and upcoming Citadel spin-off (not season 2, which has separately been confirmed) called Citadel: Diana, coming 2024.
