John Russell is a reporter.
He is largely freelance at his craft although he does have affiliations with both an American newspaper chain and a British one but he writes what catches his eye and which he thinks his contacts will pay for. Sometimes his guess misses but more often than not he is successful. His nose for the news is pretty good considering the number of years he has been doing it but that length of work is double-edged. His drive to get the story and dig deep enough to get the whole truth and let the whole world know is now tempered with the knowledge that much of the truth is uncomfortable and unwelcome.
He also knows that getting the whole truth can get him killed and even worse endanger those he loves. His beat is Germany in the era of Adolf Hitler and his minions. As the series begins just months before hostilities formally broke out between Germany and England, his every word is being perused carefully by the Gestapo and writing too much of the truth could get him kicked out or worse, locked in.
Russell is of Anglo-American nationality. His mother is American and constantly pushing to have him get out of the danger zone. His father is/was a British citizen and thus Russell can and does consider both nations home. This helps considerably when looking for what might interest readers of either country. It also gives him somewhat more freedom of movement in ever-more paranoid Germany than a German reporter might get but also makes him more suspect to the trust-nobody Nazi authorities.
He came to Germany a decade and a half before as part of his job. He liked the country and the people and he met and fell in love. Marriage followed and a son was created. The marriage did not last but his interest in Germany remained and now after so many years, it is a third home. His son is entering adolescence and Russell has a new love in Effi, a much younger woman who is an actress when she can find work. The two present the majority of reason he does not leave the growing madness that is the Third Reich for both have no desire to start over elsewhere. Until they are ready to depart, he stays, writing what he can and trying to keep everybody, if not happy, at least not homicidal.
It is while maintaining this very tenuous balance that Russell is approached by virtually everybody. A Soviet contact offers him a chance to write for Russian papers while also passing along tidbits that might be useful to their side. He finds a way to get the Gestapo to agree, not knowing his true purpose. This gives him added income while hurting a regime he is finding more and more reasons to loathe.
But as the series progresses, British Intelligence will come calling. And American Intelligence. And the Germans will find uses for him. And the Soviets never let anyone off the hook. Life gets very complicated and deadly for Russell.