Sounds like a reverse Man in the High Castle.
I had never really considered it until I saw a book in the Fort Campbell library some years ago titled Japan’s Secret War: How Japan’s Race to Build its Own Atomic Bomb Provided the Groundwork for North Korea’s Nuclear Program
Seems outrageous, right? First, the author does have some decent points. More importantly, as a writer, it sparked an idea. What if they had succeeded? What if they made two bombs and detonated one, as the author claims, in Manchuria near the end of the war. And the second? They put it on a submarine and sent it across the Pacific to the most likely target: San Francisco. But the war ended and the submarine disappeared. But what if it’s still there? At the base of the Golden Gate. With the enriched uranium on board?
And thus I have the core of a novel that is a modern day thriller and also goes back in history to the end of World War II and not just the atomic bomb program but more. My books always have a heavy dose of true history.
I ended up with The Gate which is only .99 today (8/26 and the next several days).
Here’s the slideshow for The Gate.