Not a great WW II mystery, but an interesting one. Which is more important, preserving the XX secret or preventing the attack on Pearl Harbor? Can you do both? Not if two Nazi spies have their way. There are twists and turns everywhere in this novel. And not everyone knows who is on which side... which can be fortunate.
However, I have to admit I'm a little leery of how the hero dashes all about London with a severely wounded hand, which keeps getting torn open time after time. He also gets beaten up a lot. And will he ever get any sleep?