You don't need to watch Citadel before streaming Citadel: Diana but you should know these 3 things

Citadel: Diana is coming to Prime Video on Thursday, Oct. 10. For those who don't know, the spy thriller is a spinoff of Citadel but if you're not feeling up to binge watching the original before diving into Diana's story, don't worry about it. Her show takes place in 2030, eight years after Citadel falls.

Diana is trying to flee Italy after having been a mole for the agency. She gains an unexpected ally in Edo Zani, the heir to the Italian branch of Manticore and the son of Ettore Zani. While the two series share a universe, it's not necessary to stream the original to understand what's going on.

There are, however, some plot details from the flagship that you should know before diving into this next installment in the franchise. Let us fill you in!

MAJOR spoilers ahead of Citadel season 1

What are Citadel and Manticore?

Citadel is a spy organization that was founded over 100 years ago in the franchise's universe. They started as a group of French spies who recruited operatives from around the world to join their ranks. The agency had no allegiance to any one person or nation which allowed them to ensure the safety and security of all of the world's citizens.

In contrast, Manticore is a spy network that was created by the world's wealthiest families. They are said to be concerned with amassing more power and wealth. The overall good of the globe isn't of their concern. They're also responsible for Citadel nearly being wiped out of existence.

How did Citadel fall?

The first season of the original series is a twisting plot that's shaped around how and why Citadel was destroyed from the inside by one spy. Episode 1, "The Human Enigma," detailed the mission that the agency's top operatives, Mason Kane and Nadia Sinh, were on in Italy.

While on a train where they were apprehending a target, they found out they'd been lured into a trap. This was the first time that Manticore showed their face. They revealed that all around the world, they were taking out Citadel spies and bringing the organization to its knees.

In the season 1 finale, "Secrets in Night Need Early Rains," one of the last plot twists came to light. The agent who put into motion Citadel's down fall was none other than Mason Kane. However, it was not his intention to get thousands of his fellow spies killed.

He'd given up the organization's secrets to his mother, Dahlia Archer, a UK ambassador who'd told him that she would get justice for his father, Thomas, who'd been killed by Citadel in a bombing that the agency covered up. They'd mistakenly launched missiles at a building filled with UN workers and their families when they'd been targeting a Serbian terror cell.

Dahlia said that she'd take the information to a high court but instead she gave it to Manticore in order to get revenge against Citadel. Mason didn't know she was working for the rival spy organization.

When does Citadel: Diana take place in the timeline?

Presumably, the series runs parallel to the flagship in its timeline. We'll see Diana become a Citadel spy in order to find out why her parents were killed and we'll be with her as she tries to make her escape eight years after the organization is dismantled. She's likely doing this as Mason and Nadia are regaining their memories after having been backstopped eight years prior.

We also may learn who orchestrated the attack on the train. Since it happened in the Zanis' territory, they're the most likely culprits. However, we don't know much about the family or their motives. Or if Diana was in anyway part of that mission that wound up being a trap. It'll be interesting to see how the flagship and her series may be woven together to create a more complete picture.

Stay tuned to Americans Undercover for coverage. Follow us on Facebook and X for more content. Citadel: Diana premieres Thursday, Oct. 10 on Prime Video with all six episodes.