Humble stamp dealer Otto Becker has little to do with international politics, so when he receives a surprise visit from his estranged twin brother and Nazi spy, Baron Hugo von Detner, his world is thrown into turmoil. Threatening Becker with deportation, Hugo forces him to use his shop as a front for espionage.
Conrad Veidt has two parts to play in this enjoyable wartime espionage thriller. On one hand, he is the "Baron"- the Nazi consul leading a sophisticated network of spies and saboteurs; on the other he is "Otto", the twin of that gent and a loyal citizen of the USA. When the former tries to co-opt the latter into his web of intrigue, a kerfuffle ensues and soon we have a new "Baron" - intent on dismantling the fifth column thoroughly. His plan is working well, but the Nazi's are aware that they have a spy in their midst and he must stay one step ahead of his shrewd assistant "Richten" (Martin Kosleck) and try to keep his love "Kaaren" (Ann Ayars) out of harm's way too. There are a couple of scenes where Veidt plays both characters, and the effects really work quite well; as does the story - a fairly typical plot but one that is well written, paced and performed.