In Citadel, Mason and Nadia lose their memories after Manticore’s attack. Years later, they discover that a procedure called the backstop was responsible for their memory loss.
When Nadia and Mason go to stop a man named Gregor Yovanovitch on a train, they realize a little too late that they were set up by Manticore. They manage to fight the men sent to attack them, but Gregor Yovanovitch unexpectedly blows up the train compartment.
Mason is thrown into a river, and when he is pulled out of the water, he does not remember anything about his life, not even his name. The doctor tells him that he is suffering from retrograde amnesia, which has affected his memories.
A passport was found in Mason’s pocket, and due to that, he believes that he is Kyle Conroy, not knowing that it is a fake identity created by Bernard for him. He lives his life as Kyle Conroy for eight years until Bernard finds him.
What is the backstop?
Bernard tells Mason about his past. He explains to him why he has all those scars on his body and why he keeps having visions of Nadia.
The two were Citadel spies, and every Citadel spy has a chip placed in their temporal lobe. There is also a Citadel server, and the chip uploads the memories of the spies to that server.
Whenever a spy is compromised and Citadel cannot trace them, Citadel initiates a procedure called the backstop to erase their memories via the chip so that the spies cannot remember anything about their work at Citadel.
When Nadia and Mason were attacked eight years ago, Nadia sent a Mayday call, and Bernard initiated the backstop. Nadia only had two hours before her memories were erased.
She passed out due to her injuries but was saved by a stranger, who then held her captive at his house. By the time she fought and killed him, the backstop had started, and she only got a few seconds to write down a message for herself on her arm.
Her memories were deleted, and she passed out again. When she woke up, she found herself in an unknown place, lying next to the dead body of a stranger, with a message on her arm that instructed her to go to Valencia Asha.
How can the spies regain their memories?
After the backstop, the memories of the spies are not lost forever, as they have been uploaded to the server. When Bernard and Mason get the Citadel X Case back, Bernard shows him the vials with the names of different agents stored in the case.
The agents need to be injected in the neck with that fluid. When the fluid reaches their bloodstream, they regain their memories. However, every agent just has one vial and not more than that; this is their only way to regain their memories.
Davik, who had been chasing Bernard and Mason to get to the case, shoots Bernard, who loses control of the car and crashes it. In the crash, Mason’s vial gets broken, and he loses his one and only chance to get his memories back.
He finds Nadia, who is also alive, and gives her the vial with her name on it. When Davik attacks them, Nadia injects herself with the fluid and regains her memories. She remembers her training and is able to beat Davik easily.
Apart from Nadia and Mason, Celeste, who is also known as Abby, Mason’s wife, was also backstopped. Mason accused her of being a mole and got her backstopped because he wanted to protect Nadia. Mason then asked Bernard to destroy Celeste’s vial, leaving her with no way of regaining her memories.