Emperor's Diamonds

The parallel worlds' travelers Marty and Nick are back in a human world, 1957 Miami Beach. It's totally different geo-politically from their old one. America comprises of eighty states, Russia had been impovershed by WWII and Stalin, Germany is devastated, and Japan had been obliterated after invading the US. Nick is exposed as being the last of the Romanov line and helps free the Russian people.