Joe Hawkins is a visiting professor at Oxford. Kate Farrow is a psychiatrist.
Neither professions sound like the sort that would bring membership into a group devoted to espionage but looks are often deceiving and what is often does not equal what was.
As for the was, Joe Hawkins was an operative for the U.S. State Department's highly clandestine intelligence division, working all sorts of missions in all sorts of locales around the world. Kate Farrow was for some years connected through her medical degree with MI6 helping its operatives deal with the stress of the job but also learning how to talk with and interrogate captured terrorists.
In both cases, their previous lives will cause their present ones to change and will get both of them into considerable trouble. We we first meet both, they do not know each other but as this trouble envelopes them, they will be forced to become acquainted very quickly and work together or they both will not live to talk about it.