Captain Velkov was sent chief of a border post near the village of Novi Izvor, where he was a partisan. In Novi Izvor a celebration is being prepared to mark the switching on of the electricity. Saboteurs cut the cables, killed the watchman and set fire to the machinery on the farm.

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.

The film is dedicated to the uprising, which broke out in Bulgaria in September 1923. All characters, with the exception of the leaders of the uprising Georgi Dimitrov and Vasil Kolarov, are symbolic characters. The central figures, Stefan and Peter, impersonate the motive forces behind the uprising - the workers and the peasants. They are involved in worker's strikes, in the stormy events of the First World War and the Soldier's uprising in 1918. They also participate in the bloody clashes of the September uprising and suffer its defeat after they have seen too late the need for concerted action by communists and agrarians.

The successful factory owner Sasho Kamenov marries Maria. Sasho wants to surprise Maria with a villa on the seaside. He commissions the project to architect Karshev who begins to court Maria. Kamenov sends his wife to the seaside. There Maria meets Karshev. She feels unwell in the car and the medical examination reveals that she is expecting a baby. In her joy at the news she accepts the architect's invitation to go boating. A raging storm keeps Maria at Karshev's villa. Kamenov accuses his wife of adultery and chases her away. After a while he repents and goes abroad in search of his wife... Sasho discovers his wife singing in a club in Nice. She tells him everything, he asks her to forgive him and soon the happy family makes a photograph.