Instead of a rumour that German physicists are working on the bomb, a rumour occurs that they’re working on a pact. You are the equivalent of the Manhattan project, but you’re trying to create a magical superweapon. Your campaign: beat the Germans to the wish spell.
Start the whole team on magic classes, and have them chase after rumours in a 1940 WW2 setting.
Or a variant of Turtledove’s Worldwar alt-history campaign where aliens invade mid war. Except it’s demons.