The Two Headed Spy (1958)

World War II spy thriller supposedly based on true story. A British secret agent successfully infiltrates Nazi military and achieves the rank of General during World War II. He gains full confidence of entire Nazi high command, including Führer Adolf Hitler, save one suspecting German officer. All the while, the spy passes war-winning information to Allies assisted by two loyal Berlin contacts, first a man, then a nightclub singer. A war drama with love-interest relationship and a cliffhanger finale. Also memorable is frightening Adolf Hitler always portrayed from behind, face unseen, but with snarling, tyrannical voice.