Ethan Harris is an IT specialist.
Amy Knight is an investigative journalist.
The activities that bring these two people who, prior to the first recorded adventure did not know each other - had never met - take place in 2015.
First on Harris. We first meet him in 2015 as he prepares to bury his wife, Rachel, the victim of murder. He is left with their two-year-old daughter, Katy, who is being watched largely by his mother-in-law, a woman who always thought Harris was beneath her and her late daughter. Harris, a man in his early 40's, is IT director at MitaSimi, "a small investment bank noted for punching well above its weight in the financial world". Getting by and providing for his daughter seems to be his only goal.
Second on Knight. She has been a reporter for quite some time; her "first big story ... took place in Berlin in the 1991; it was on East Berliners' attitudes after the fall of the Wall" and her experience dealing with both the Stasi during the end of East Germany's existence and with the BND after the reunification is substantial. In the latter case it was not really to suppress her reporting, it seems, but to learn who was leaking secret information to her. Nevertheless, her experience dealing with German intelligence communities is extensive, albeit from the outside perspective.
As mentioned above, Harris and Knight do not know each other and neither of them is employed in any way by any governmental intelligence department. They will, however, get thrown together by people who do work for such organizations and to stay alive, both will have to learn a lot of tricks decidedly outside their normal lives.