When Fritz Leiber sees a Zeppelin moored at the Empire State Building one afternoon in 1973 , he realizes that he has shifted into another timeline — one where a more decisive defeat of Germany at the end of the First World War led to greater international prosperity and a deeper , more acceptable peace , with the result that America was willing to sell Germany helium for use in airships , thereby preventing the Hindenburg disaster . Also , the year has changed from 1973 to 1937 , and Leiber has become a patriotic-but-peaceful German airship engineer named Adolf Hitler
Hindenburg disaster
Hindenburg disaster
Catch That Zeppelin!