Constantinople, 1883. During an outing to the Black Island Edith, the adopted daughter of the French ambassador, is saved by Kalin the Eagle. She learns that he is a Bulgarian revolutionary from the April Uprising of 1876. With her help Kalin the Eagle escapes and returns to the liberated Bulgaria, where he is drawn to the socialist movement. Edith finds out that Kalin is in fact her father, and sets out in search of him. Kalin the Eagle is notable as the first movie made by the nationalized film industry after World War II in the newly formed People's Republic of Bulgaria.

In 1933 Berlin, Bulgarian communist Georgi Dimitrov is caught up in the Reichstag fire trials when Nazis seek to frame communists. Despite orchestrated provocations and mass repression, Dimitrov’s defiant courtroom defense exposes the baseless charges, forcing his acquittal and securing him political asylum in the Soviet Union.