Mason Kane lives a quiet family life with no memory of his days as a secret agent for Citadel, an independent global spy agency. The former spy (played by Richard Madden) and his partner Nadia Sinh (played by Priyanka Chopra Jonas) were presumed dead eight years prior when they were ambushed by operatives of a powerful syndicate called Manticore. Citadel follows the two spies as they’re dragged back into the world of espionage to stop Manticore while fighting to restore their own memories.