The true story of a German agent sent to the USA in 1944 in order to stop the development of the atomic bomb.

After drinking too much alcohol, King Michael XXXVII promptly forgets his own wedding date! To avoid a scandal, his police minister asks the writer Peter Petroni, who looks deceptively like the king, to stand in for the alcoholic Michael at the ceremony. The only trouble is that the game quickly turns serious - because when Peter catches sight of "his" bride at the altar, it's love at first sight...

As the title "The Queen's Heart" suggests, this early German black and white version of Mary Queen of Scott's eventful reign and death focuses on her emotional perception rather lyrically, with some songs, mainly by her.