Clara Vine is an agent with British Intelligence.
She did not plan to be an agent and she definitely did not receive any actual training in the cloak and dagger business. She is an actress, just starting out, and looking for opportunities to improve her craft and show her talent. A party In London would let her know of opportunities in Germany for someone of her background, being of Anglo-German ancestry. After some consideration, she heads east to Berlin.
It would be while in that capital that she would be introduced to the up-and-coming in society which in 1933 were the members of the Nazi party having just won a good number of seats in the government. It would also be the time that she meets Leo Quinn, an agent with British Intelligence who is sharp enough to recognize an opportunity when he sees it. Once convinced by Quinn to help her native country keep up with what was transpiring in Germany, Vine will find herself with two careers, acting and spying.
In the beginning she will find life challenging and exciting but not really, truly dangerous, at least in her mind. As time progresses and the extremes the Nazi leadership will go to become far too obvious, she, being a very smart person, will know that one slip will get her kicked out of the country or worse, become a guest of the ultra-frightening Gestapo. And when the hostilities actually break out, staying and spying become extremely important and extremely deadly. But leaving and heading home where it would be safer is not really an option to Vine when the people she needs to monitor start looking to her for information, giving up far more in the process.