Craig Page is the head of the European Counterterrorism Agency.
The ECA is a brand-new small international department created to coordinate the fight against any and all terrorism in the many countries in Europe. The agency was created largely in thanks for work Page did in foiling a particularly nasty plot in Italy but its necessity was never at issue. Interpol concentrated on crime, not terrorism, and no individual country's counter-terrorism department could cross borders without issue.
At the start of the recorded series, the ECA did not yet exist but Page, living in Europe at the time, had just agreed to help out on the matter that would bring its creation about. He was living there for the previous six months as he started his private security consultancy in the wake of his walking away from a long and highly successful career with the CIA. This separation from the Company was his decision but one forced upon him by another.
For all of his adult life, Page had been an operative with the CIA and later a hands-on field leader. His specialty was the Middle East and his familiarity with that region and many of its players, both good and bad, was impressive. Even as he helped raise a daughter during the more than two decades in the covert work, he became the man to go to with any question about who might be doing what in that hotbed region. It was certain that he would stay until he retired.
That ended when the new Director of the CIA, a man named Kirby, took over. An appointee in response to his father's very generous contributions to the current President's elections, Kirby took an almost instant dislike to Page. This boiling antagonism reached eruption stage when Page disobeyed Kirby's instructions to stand down from a job and instead followed a dangerous terrorist to the States and stopped his plot. This earned Page a personal commendation from the President and sealed the hatred of Kirby. Within a very short time, Page's position with the CIA was eliminated and Page knew it was time for him to go.
As the series progresses, a personal tragedy for Page puts him in close contact with Elizabeth Crowder, a celebrated international journalist whose work had earned her plenty of plaudits including the coveted Pulitzer. As the two grieved their loss together, they also worked to find the truth and bring to justice the ones at fault. Afterwards, they realized how much they liked each other and how well they worked together. They would remain close and Crowder is an integral part of the series.