Dragan 'Dan' Kelly is an agent with MI5.
When we first meet him, he is nowhere close to that career path. He is a relatively new Second Lieutenant serving aboard a British frigate in the frigid waters off Norway, the ship being part of the extremely hazardous convoy protection detail trying to keep vitally needed cargo ships safe from U-boats. A run-in with one of those feared menaces of the deep would change his life completely.
Kelly is, as one man put it, certainly not English. "Irish father, Serbian mother. Born in Wales, raised in Scotland...in attitude, beliefs, and convictions he is most definitely British." Through his mother, he spent several summers working in the vineyards of the Mosel Valley, from where he learned to speak German as a native. He is an educated man who had attended Cambridge prior to the war continuing on to do postgraduate work. That was interrupted when the hostilities began and he joined the Royal Navy.
Playing a major role in Kelly's life after she helps rescue him, joining him eventually in his adventures, is a Norwegian woman named Sybilla Thorstaadt. She is married, though not so happily, to Gunnar. When we first meet her, it is said that "she moved with the grace of an athlete and had a classical figure which was slim rather than thin. She was a little older than [Kelly], he guessed that she must be in her mid-twenties. The most notable feature of the woman was her face. She smiled frequently, displaying perfect white teeth when she did so, but she didn't just smile with her mouth, her whole face lit up and her beautiful blue eyes sparkled. Her face was prettily edged by hair that was cut to shoulder length with a light natural wave. It was the almost white blonde rarely seen outside of Scandinavia. Her skin was lightly tanned and flawless. She was quite exquisite."
Also pretty important in his life and his missions is Wolfgang Rahn, a 'mad' priest who has had his share of adventurous living (think French Foreign Legion) and then got the 'call from God'. Now a man of the cloth, he is a key player in the local Resistance movement.