Billy Boyle, a young Irish-American cop from Boston has just made detective - with a little help from his cop relatives and friends - when World War II breaks out. His rabidly anti-English family calls on his mother's distant cousin, Mamie, married to a general, to wangle a staff job for him far from the fighting. But instead of a "safe, cushy" stateside assignment, he is ordered to London, still undergoing the Blitz.