David Llewellyn is an agent for the President.
Actually employed by the State Department, Llewellyn had been a combination diplomat and secret operative, specializing in activities in the Scandinavian area from where he could also keep on eye on Soviet operations. When an agent for the other side tried to eliminate him but instead killed his wife, Katherine, he withdrew from the clandestine work and concentrated on the diplomacy side, eventually becoming Acting Ambassador to Sweden at the death of the formal ambassador.
Fluent in numerous languages, including those of Sweden and surrounding countries, Llewellyn was expecting a permanent posting there when he was called into the President's office at the beginning of the series. Instead, the Commander-in-Chief asked him to help in another arena, one that would again require the wearing of both hats. It was not a role he wanted to play but his friendship with President before that man took office, and his respect for the man now that he had the job, did not give him any room to argue.
Interestingly, the new work that the Chief Executive has for Llewellyn, a man extremely knowledgeable about northern Europe and the Scandinavian region, will take him far south into the hot, arid region of the Middle East.
While Llewellyn is not a young man anymore, being in his early 40s, he is still an imposing man standing well above 6' and in excellent physical condition. If it were not for the spreading gray through his dark hair, he would easily pass for a man a decade younger.
In his new assignment to Israel, Llewellyn meets and eventually falls in love with an Israeli agent named Daniella Zadik, a resourceful and efficient operative who plays a vital role in both documented adventures.