Billy, a young, newly promoted detective from South Boston when he faces the draft, lacks a few credentials, but his father is a power in the police department, and his mother is kin to Mamie Eisenhower. He's learned a little about detective work from Dad, but he's ill-educated, having scraped though high school and read nothing more complex that Sherlock Holmes stories. His boss and co-workers in London know his background and treat him with ill-concealed contempt.

Still, he's Ike's choice to investigate any chicanery that might go on among the headquarters officers, so he's quickly brought up to date on current plans for an invasion of Norway, which is to be the first Allied step toward routing the Germans. He's taken to a conference where he meets the exiled King of Norway, learns about the political in-fighting in the Norwegian high command, and plays war games with soldiers of the Norwegian brigade that's training in England.

Billy is strictly a minor player until one of two rivals to become the King's primary advisor is found dead in his room with a suicide note on his desk. Only Billy can see that it's a murder, despite the note. His stock goes up as he methodically follows every lead and discovers evidence to prove his theory. With the help of Second Officer Daphne Seaton and her noble Polish lover, he keeps working until he turns up a connection between the murderer and whoever is feeding the invasion plans to the enemy.

Billy is plunged into the affairs of the Norwegian staff, but thoroughly baffled when a number of suspects emerge. Then more murders ensue, and Billy quickly proves they're connected to the cases already under investigation. By that time his superiors are listening to him, and his job of solving the crimes while avoiding any political embarrassment to the people he's working for becomes ever more complex. Even when he's found the culprits, after an adventure more dangerous than those most infantrymen face, Billy is faced with momentous decisions he never thought would be part of his job.

Good characters drive a good plot, and Benn delivers. He writes well. Billy's crush on Second Officer Seaton never goes anywhere, but he finds her sister, whom he gets to know only toward the end of the book, even more enticing. The wartime atmosphere and the hidden problems bedeviling the high command come through well. The only shortcoming of this novel is that Billy seems a good deal too smart, his mind too quick, and his vocabulary a bit too extensive to fit a character first presented as a yokel riding high on his family's influence. That turns out to be fairly easy to forgive.

Billy is, after all, an engaging hero, and most readers who like historical mysteries will find this fast-moving story well worth reading.