Billy Boyle is a police detective.
He is definitely not a spy and would not want to be one. He is pleased to be what he is which is a newly promoted detective with the Boston Police Department. Well, he was until he gets called to serve in the Second World War. He was not thrilled with that development, not because he was unpatriotic but because it certainly meant having to leave Boston. In truth, he seldom left his turf of South Boston if he could avoid it, let alone the country. Luckily he was assured that 'the fix was in' and he would be spending his service time helping out as a staff officer at the War Department in D.C.
Boyle is honest with us in another way when he admits that while he knows he will be pretty good at being a detective, the exam to pass was a bear because he was 'no scholar'. He was not at all upset when "a few sheets from the test sort of found their way into his locker a couple of days before the exam". And having an uncle on the promotions board did not hurt. Boyle's skill at solving cases came to him naturally aided by the fact that his father was a very experienced homicide detective and Boyle had grown up watching him figure things out methodically.
Another thing that Boyle reveals is that he and his immediate family were not only proud Boston Irish, they were ultra proud Irish, period, strong supporters of the IRA and all that and the thought of having to go into actual battle on behalf of the English - well, not going to happen, was Boyle's attitude. Imagine then the surprise and 'annoyance' he felt when he learned his cushy job in DC working for one distant uncle was switched to working in London for another distant uncle. Uncle Ike. As in General Dwight D. Eisenhower, commander of the European Theater.
By the way, this was no clerical error or military snafu. As he explains, "I love my mom but I had to think that maybe this was not one of her best ideas".
So we have Billy Boyle living in England and working on behalf of an uncle he had met a few times in the past but was not especially close to. And we have a Boyle who has no idea what is expected of him since he was not really a soldier, he was a police detective.
That is when Uncle Ike reveals his need for someone like Boyle and it was both simple and complex. As huge numbers of Americans were being prepared for shipment to Europe to fight the Axis, there were certain to be a fair number of bad apples in the mix, men who would see an opportunity to take advantage of things like the black market and smuggling, not to mention theft and even the occasional murder. And often it would far better for everyone's morale if these people were caught and dealt with out of the limelight; punishment fitting the crime and all but without publicity. That's where a detective someone like Boyle would come in, someone who could not only solve a mystery but also make a problem go away.
Uncle Ike was pretty smart in his predictions but not even he would have imagined how extensive the work his nephew would get involved with. Smugglers and black marketeers, yes. Thieves and even murderers, yes. But also traitors and turncoats and foreign spies and rogue operatives. Toss in angry and vengeful Resistance and Partisan members. Boyle would need all of his South Boston cop instincts to stay alive.